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    Standard library header <algorithm>

    From zh.cppreference.net
    C++
    Standard library headers

    此头文件属于 algorithm 库。

    目录

    Includes

    (C++11)
    		std::initializer_list class template

    Classes

    Defined in namespace std::ranges
    Return types (C++20)
    (C++20)
    		provides a way to store an iterator and a function object as a single unit
    (class template)
    (C++20)
    		provides a way to store two iterators as a single unit
    (class template)
    (C++20)
    		provides a way to store two iterators as a single unit
    (class template)
    (C++20)
    		provides a way to store three iterators as a single unit
    (class template)
    (C++20)
    		provides a way to store three iterators as a single unit
    (class template)
    (C++20)
    		provides a way to store two objects or references of the same type as a single unit
    (class template)
    (C++20)
    		provides a way to store an iterator and a boolean flag as a single unit
    (class template)
    (C++23)
    		provides a way to store an iterator and a value as a single unit
    (class template)
    (C++23)
    		provides a way to store an iterator and a value as a single unit
    (class template)

    Functions

    非修改序列操作
    (C++11)(C++11)(C++11)
    		 检查谓词是否对范围中的所有、任意或无元素true
    (函数模板 & 算法函数对象)
    (C++20)(C++20)(C++20)
    		将一元函数对象应用于来自范围
    的元素 &(函数模板
    ranges::for_each
    for_each_n
    		 (C++17)
    将函数对象应用于序列中的前N个元素 &(函数模板
    ranges::for_each_n
    		count_if
    返回满足特定条件的元素数量 &(函数模板
    ranges::count_if(C++20)
    		mismatch
    找到两个范围第一个不同元素的位置 &(函数模板
    ranges::mismatch
    find_if_not
    		 (C++11)
    找到第一个满足特定条件的元素 &(函数模板
    ranges::find_if_not(C++20)(C++20)
    		find_end
    在指定范围中查找元素的最后一个序列 &(函数模板
    ranges::find_end
    		find_first_of
    搜索元素集合中的任意一个 &(函数模板
    ranges::find_first_of
    		adjacent_find
    查找第一对相等的相邻元素（或满足给定谓词的元素） &(函数模板
    ranges::adjacent_find
    		search
    搜索元素范围的第一次出现 &(函数模板
    ranges::search
    		search_n
    在范围中搜索第一个连续出现指定次数的元素 &(函数模板
    ranges::search_n
    (C++20)
    修改序列操作
    (C++11)
    		 将元素范围复制到新位置
    (函数模板 & 算法函数对象)
    (C++20)(C++20)
    (C++11)
    		 将指定数量的元素复制到新位置
    (函数模板 & 算法函数对象)
    (C++20)
    		以逆序复制元素范围
    (函数模板 & 算法函数对象)
    (C++20)
    (C++11)
    		 将元素范围移动到新位置
    (函数模板 & 算法函数对象)
    (C++20)
    (C++11)
    		 以逆序将元素范围移动到新位置
    (函数模板 & 算法函数对象)
    (C++20)
    		将给定值赋值给范围内的每个元素
    (函数模板 & 算法函数对象)
    (C++20)
    		将给定值赋值给范围内 N 个元素
    (函数模板 & 算法函数对象)
    (C++20)
    		将函数应用于元素范围，并将结果存储到目标范围
    (函数模板 & 算法函数对象)
    (C++20)
    		将连续函数调用的结果赋值给范围内的每个元素
    (函数模板 & 算法函数对象)
    (C++20)
    		将连续函数调用的结果赋值给范围内 N 个元素
    (函数模板 & 算法函数对象)
    (C++20)
    		移除满足特定标准的元素
    (函数模板 & 算法函数对象)
    (C++20)(C++20)
    		复制元素范围，同时忽略满足特定标准的元素
    (函数模板 & 算法函数对象)
    (C++20)(C++20)
    		将所有满足特定标准的值替换为另一个值
    (函数模板 & 算法函数对象)
    (C++20)(C++20)
    		复制范围，并将满足特定标准的元素替换为另一个值
    (函数模板 & 算法函数对象)
    (C++20)(C++20)
    		交换两个对象的值
    (函数模板)
    		交换两个元素范围
    (函数模板 & 算法函数对象)
    (C++20)
    		交换两个迭代器所指向的元素
    (函数模板)
    		反转范围内元素的顺序
    (函数模板 & 算法函数对象)
    (C++20)
    		创建一个反转后的范围副本
    (函数模板 & 算法函数对象)
    (C++20)
    		旋转范围内元素的顺序
    (函数模板 & 算法函数对象)
    (C++20)
    		复制并旋转元素范围
    (函数模板 & 算法函数对象)
    (C++20)
    (C++20)(C++20)
    		 移动范围内的元素
    (函数模板 & 算法函数对象)
    (C++23)(C++23)
    (直到 C++17)(C++11)
    		 随机重排范围内的元素
    (函数模板 & 算法函数对象)
    (C++20)
    (C++17)
    		 从序列中随机选取 N 个元素
    (函数模板 & 算法函数对象)
    (C++20)
    		移除范围内连续的重复元素
    (函数模板 & 算法函数对象)
    (C++20)
    		创建某个元素范围的副本，其中不包含连续重复项
    (函数模板 & 算法函数对象)
    (C++20)
    分区操作
    (C++11)
    		 判断范围是否按给定谓词进行分区
    (函数模板 & 算法函数对象)
    (C++20)
    		将元素范围分成两组
    (函数模板 & 算法函数对象)
    (C++20)
    (C++11)
    		 复制一个范围，同时将元素分成两组
    (函数模板 & 算法函数对象)
    (C++20)
    		将元素分成两组，同时保留每组内的相对顺序
    (函数模板 & 算法函数对象)
    (C++20)
    (C++11)
    		 定位已分区范围的分区点
    (函数模板 & 算法函数对象)
    (C++20)
    排序操作
    (C++11)
    		 检查一个范围是否已排序
    (函数模板 & 算法函数对象)
    (C++20)
    (C++11)
    		 查找最大的已排序子范围
    (函数模板 & 算法函数对象)
    (C++20)
    		对一个范围内的元素进行排序
    (函数模板 & 算法函数对象)
    (C++20)
    		对一个范围的前N个元素进行排序
    (函数模板 & 算法函数对象)
    (C++20)
    		复制并部分排序一个范围内的元素
    (函数模板 & 算法函数对象)
    (C++20)
    		对一个范围内的元素进行排序，同时保持等价元素的相对顺序
    (函数模板 & 算法函数对象)
    (C++20)
    		找到如果范围已排序时的第N个元素
    (函数模板 & 算法函数对象)
    (C++20)
    二分查找操作（在已排序的范围上）
    		使用二分查找寻找第一个不小于给定值的元素
    (函数模板 & 算法函数对象)
    (C++20)
    		使用二分查找寻找第一个大于给定值的元素
    (函数模板 & 算法函数对象)
    (C++20)
    		使用二分查找判断一个元素是否存在于范围中
    (函数模板 & 算法函数对象)
    (C++20)
    		使用二分查找寻找与给定值相等的元素范围
    (函数模板 & 算法函数对象)
    (C++20)
    对已排序范围的其他操作
    		合并两个已排序范围
    （函数模板 & 算法函数对象）
    (C++20)
    		就地合并两个有序范围
    （函数模板 & 算法函数对象）
    (C++20)
    集合操作（针对已排序范围）
    		确定一个序列是否为另一个序列的子序列
    (函数模板 & 算法函数对象)
    (C++20)
    		计算两个集合之间的差集
    (函数模板 & 算法函数对象)
    (C++20)
    		计算两个集合的交集
    (函数模板 & 算法函数对象)
    (C++20)
    		计算两个集合的对称差
    (函数模板 & 算法函数对象)
    (C++20)
    		计算两个集合的并集
    (函数模板 & 算法函数对象)
    (C++20)
    堆操作
    (C++11)
    		 检查给定范围是否为最大堆
    (函数模板 & 算法函数对象)
    (C++20)
    (C++11)
    		 查找最大的子范围，该子范围是最大堆
    (函数模板 & 算法函数对象)
    (C++20)
    		从一个元素范围创建最大堆
    (函数模板 & 算法函数对象)
    (C++20)
    		向最大堆添加一个元素
    (函数模板 & 算法函数对象)
    (C++20)
    		从最大堆中移除最大元素
    (函数模板 & 算法函数对象)
    (C++20)
    		将最大堆转换为按升序排列的元素范围
    (函数模板 & 算法函数对象)
    (C++20)
    最小/最大操作
    		返回给定值中的较大者
    (函数模板 & 算法函数对象)
    (C++20)
    		返回范围中最大的元素
    (函数模板 & 算法函数对象)
    (C++20)
    		返回给定值中的较小者
    (函数模板 & 算法函数对象)
    (C++20)
    		返回范围中最小的元素
    (函数模板 & 算法函数对象)
    (C++20)
    (C++11)
    		 返回两个元素中的较小者和较大者
    (函数模板 & 算法函数对象)
    (C++20)
    (C++11)
    		 返回范围中最小的和最大的元素
    (函数模板 & 算法函数对象)
    (C++20)
    (C++17)
    		 将值限制在一对边界值之间
    (函数模板 & 算法函数对象)
    (C++20)
    比较操作
    		确定两个元素集合是否相同
    (函数模板 & 算法函数对象)
    (C++20)
    		按字典序比较两个范围
    (函数模板 & 算法函数对象)
    (C++20)
    (C++20)
    		 使用三路比较比较两个范围
    (函数模板)
    排列操作
    (C++11)
    		 判断一个序列是否为另一个序列的排列
    (函数模板 & 算法函数对象)
    (C++20)
    		生成范围内元素的下一个较大的字典序排列
    (函数模板 & 算法函数对象)
    (C++20)
    		生成范围内元素的下一个较小的字典序排列
    (函数模板 & 算法函数对象)
    (C++20)

    Function-like entities (C++20)

    Defined in namespace std::ranges
    Non-modifying sequence operations
    (C++20) (C++20) (C++20)
    		checks if a predicate is true for all, any or none of the elements in a range
    (algorithm function object)
    (C++20)
    		applies a unary function object to elements from a range
    (algorithm function object)
    (C++20)
    		applies a function object to the first N elements of a sequence
    (algorithm function object)
    (C++20) (C++20)
    		returns the number of elements satisfying specific criteria
    (algorithm function object)
    (C++20)
    		finds the first position where two ranges differ
    (algorithm function object)
    (C++20) (C++20) (C++20)
    		finds the first element satisfying specific criteria
    (algorithm function object)
    (C++23) (C++23) (C++23)
    		finds the last element satisfying specific criteria
    (algorithm function object)
    (C++20)
    		finds the last sequence of elements in a certain range
    (algorithm function object)
    (C++20)
    		searches for any one of a set of elements
    (algorithm function object)
    (C++20)
    		finds the first two adjacent items that are equal (or satisfy a given predicate)
    (algorithm function object)
    (C++20)
    		searches for the first occurrence of a range of elements
    (algorithm function object)
    (C++20)
    		searches for the first occurrence of a number consecutive copies of an element in a range
    (algorithm function object)
    (C++23) (C++23)
    		checks if the range contains the given element or subrange
    (algorithm function object)
    (C++23)
    		checks whether a range starts with another range
    (algorithm function object)
    (C++23)
    		checks whether a range ends with another range
    (algorithm function object)
    Fold operations
    (C++23)
    		left-folds a range of elements
    (algorithm function object)
    (C++23)
    		left-folds a range of elements using the first element as an initial value
    (algorithm function object)
    (C++23)
    		right-folds a range of elements
    (algorithm function object)
    (C++23)
    		right-folds a range of elements using the last element as an initial value
    (algorithm function object)
    (C++23)
    		left-folds a range of elements, and returns a pair (iterator, value)
    (algorithm function object)
    (C++23)
    		left-folds a range of elements using the first element as an initial value, and returns a pair (iterator, optional )
    (algorithm function object)
    修改序列操作
    (C++20)(C++20)
    		 将元素范围复制到新位置
    (算法函数对象)
    (C++20)
    		 将指定数量的元素复制到新位置
    (算法函数对象)
    (C++20)
    		 以逆序复制元素范围
    (算法函数对象)
    (C++20)
    		 将元素范围移动到新位置
    (算法函数对象)
    (C++20)
    		 以逆序将元素范围移动到新位置
    (算法函数对象)
    (C++20)
    		 为元素范围赋予特定值
    (算法函数对象)
    (C++20)
    		 为指定数量的元素赋予值
    (算法函数对象)
    (C++20)
    		 将函数应用于元素范围
    (算法函数对象)
    (C++20)
    		 将函数的结果保存到范围中
    (算法函数对象)
    (C++20)
    		 保存 N 次函数应用的结果
    (算法函数对象)
    (C++20)(C++20)
    		 移除满足特定条件的元素
    (算法函数对象)
    (C++20)(C++20)
    		 复制元素范围，并省略那些满足特定条件的元素
    (算法函数对象)
    (C++20)(C++20)
    		 将所有满足特定条件的值替换为另一个值
    (算法函数对象)
    (C++20)(C++20)
    		 复制范围，并将满足特定条件的元素替换为另一个值
    (算法函数对象)
    (C++20)
    		 交换两个元素范围
    (算法函数对象)
    (C++20)
    		 反转范围中元素的顺序
    (算法函数对象)
    (C++20)
    		 创建反转后的范围副本
    (算法函数对象)
    (C++20)
    		 旋转范围中元素的顺序
    (算法函数对象)
    (C++20)
    		 复制并旋转元素范围
    (算法函数对象)
    (C++23)(C++23)
    		 平移范围中的元素
    (算法函数对象)
    (C++20)
    		 从序列中选择 N 个随机元素
    (算法函数对象)
    (C++20)
    		 随机重新排序范围中的元素
    (算法函数对象)
    (C++20)
    		 移除范围中的连续重复元素
    (算法函数对象)
    (C++20)
    		 创建不包含连续重复元素的某个元素范围的副本
    (算法函数对象)
    划分操作
    (C++20)
    		 确定范围是否由给定谓词划分
    (算法函数对象)
    (C++20)
    		 将元素范围分成两组
    (算法函数对象)
    (C++20)
    		 复制一个范围并将元素分成两组
    (算法函数对象)
    (C++20)
    		 将元素分成两组，同时保留每组内的相对顺序
    (算法函数对象)
    (C++20)
    		 定位已划分范围的分界点
    (算法函数对象)
    排序操作
    (C++20)
    		 检查范围是否已排序
    (algorithm function object)
    (C++20)
    		 找到最大的已排序子范围
    (algorithm function object)
    (C++20)
    		 对范围内的元素进行排序
    (algorithm function object)
    (C++20)
    		 对范围内前N个元素进行排序
    (algorithm function object)
    (C++20)
    		 复制并部分排序范围内的元素
    (algorithm function object)
    (C++20)
    		 对范围内的元素进行排序，同时保持等价元素的相对顺序
    (algorithm function object)
    (C++20)
    		 找到范围排序后的第N个元素
    (algorithm function object)
    二分查找操作（在已排序范围上）
    (C++20)
    		 使用二分查找查找第一个不小于给定值的元素
    (算法函数对象)
    (C++20)
    		 使用二分查找查找第一个大于给定值的元素
    (算法函数对象)
    (C++20)
    		 使用二分查找确定元素是否存在于范围中
    (算法函数对象)
    (C++20)
    		 使用二分查找查找与给定值匹配的元素范围
    (算法函数对象)
    Other operations on sorted ranges
    (C++20)
    		merges two sorted ranges
    (algorithm function object)
    (C++20)
    		merges two ordered ranges in-place
    (algorithm function object)
    集合操作（在有序范围上）
    (C++20)
    		 判断一个序列是否为另一个的子序列
    （算法函数对象）
    (C++20)
    		 计算两个集合的差集
    （算法函数对象）
    (C++20)
    		 计算两个集合的交集
    （算法函数对象）
    (C++20)
    		 计算两个集合的对称差
    （算法函数对象）
    (C++20)
    		 计算两个集合的并集
    （算法函数对象）
    堆操作
    (C++20)
    		 检查给定范围是否为最大堆
    (算法函数对象)
    (C++20)
    		 寻找最大的子范围，其为最大堆
    (算法函数对象)
    (C++20)
    		 从元素范围创建最大堆
    (算法函数对象)
    (C++20)
    		 向最大堆添加元素
    (算法函数对象)
    (C++20)
    		 从最大堆移除最大元素
    (算法函数对象)
    (C++20)
    		 将最大堆转换成元素的有序范围
    (算法函数对象)
    Minimum/maximum operations
    (C++20)
    		returns the greater of the given values
    (algorithm function object)
    (C++20)
    		returns the largest element in a range
    (algorithm function object)
    (C++20)
    		returns the smaller of the given values
    (algorithm function object)
    (C++20)
    		returns the smallest element in a range
    (algorithm function object)
    (C++20)
    		returns the smaller and larger of two elements
    (algorithm function object)
    (C++20)
    		returns the smallest and the largest elements in a range
    (algorithm function object)
    (C++20)
    		clamps a value between a pair of boundary values
    (algorithm function object)
    比较操作
    (C++20)
    		 确定两个元素集合是否相同
    (算法函数对象)
    (C++20)
    		 按字典序比较两个范围
    (算法函数对象)
    Permutation operations
    (C++20)
    		determines if a sequence is a permutation of another sequence
    (algorithm function object)
    (C++20)
    		generates the next greater lexicographic permutation of a range of elements
    (algorithm function object)
    (C++20)
    		generates the next smaller lexicographic permutation of a range of elements
    (algorithm function object)

    概要 

    // mostly freestanding
#include <initializer_list>
namespace std {
  namespace ranges {
    // algorithm result types
    template<class I, class F>
      struct in_fun_result;
    template<class I1, class I2>
      struct in_in_result;
    template<class I, class O>
      struct in_out_result;
    template<class I1, class I2, class O>
      struct in_in_out_result;
    template<class I, class O1, class O2>
      struct in_out_out_result;
    template<class T>
      struct min_max_result;
    template<class I>
      struct in_found_result;
    template<class I, class T>
      struct in_value_result;
    template<class O, class T>
      struct out_value_result;
  }
  // non-modifying sequence operations
  // all of
  template<class InputIter, class Pred>
    constexpr bool all_of(InputIter first, InputIter last, Pred pred);
  template<class ExecutionPolicy, class ForwardIter, class Pred>
    bool all_of(ExecutionPolicy&& exec, // freestanding-deleted
                ForwardIter first, ForwardIter last, Pred pred);
  namespace ranges {
    template<input_iterator I, sentinel_for<I> S, class Proj = identity,
             indirect_unary_predicate<projected<I, Proj>> Pred>
      constexpr bool all_of(I first, S last, Pred pred, Proj proj = {});
    template<input_range R, class Proj = identity,
             indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
      constexpr bool all_of(R&& r, Pred pred, Proj proj = {});
  }
  // any of
  template<class InputIter, class Pred>
    constexpr bool any_of(InputIter first, InputIter last, Pred pred);
  template<class ExecutionPolicy, class ForwardIter, class Pred>
    bool any_of(ExecutionPolicy&& exec, // freestanding-deleted
                ForwardIter first, ForwardIter last, Pred pred);
  namespace ranges {
    template<input_iterator I, sentinel_for<I> S, class Proj = identity,
             indirect_unary_predicate<projected<I, Proj>> Pred>
      constexpr bool any_of(I first, S last, Pred pred, Proj proj = {});
    template<input_range R, class Proj = identity,
             indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
      constexpr bool any_of(R&& r, Pred pred, Proj proj = {});
  }
  // none of
  template<class InputIter, class Pred>
    constexpr bool none_of(InputIter first, InputIter last, Pred pred);
  template<class ExecutionPolicy, class ForwardIter, class Pred>
    bool none_of(ExecutionPolicy&& exec, // freestanding-deleted
                 ForwardIter first, ForwardIter last, Pred pred);
  namespace ranges {
    template<input_iterator I, sentinel_for<I> S, class Proj = identity,
             indirect_unary_predicate<projected<I, Proj>> Pred>
      constexpr bool none_of(I first, S last, Pred pred, Proj proj = {});
    template<input_range R, class Proj = identity,
             indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
      constexpr bool none_of(R&& r, Pred pred, Proj proj = {});
  }
  // contains
  namespace ranges {
    template<input_iterator I, sentinel_for<I> S, class Proj = identity,
             class T = projected_value_t<I, Proj>>
      requires indirect_binary_predicate<ranges::equal_to, projected<I, Proj>, const T*>
      constexpr bool contains(I first, S last, const T& value, Proj proj = {});
    template<input_range R, class Proj = identity,
             class T = projected_value_t<iterator_t<R>, Proj>>
      requires indirect_binary_predicate<ranges::equal_to,
                                         projected<iterator_t<R>, Proj>, const T*>
      constexpr bool contains(R&& r, const T& value, Proj proj = {});
    template<forward_iterator I1, sentinel_for<I1> S1,
             forward_iterator I2, sentinel_for<I2> S2,
             class Pred = ranges::equal_to, class Proj1 = identity,
             class Proj2 = identity>
      requires indirectly_comparable<I1, I2, Pred, Proj1, Proj2>
      constexpr bool contains_subrange(I1 first1, S1 last1, I2 first2, S2 last2,
                                       Pred pred = {}, Proj1 proj1 = {},
                                       Proj2 proj2 = {});
    template<forward_range R1, forward_range R2,
             class Pred = ranges::equal_to, class Proj1 = identity,
             class Proj2 = identity>
      requires indirectly_comparable<iterator_t<R1>, iterator_t<R2>, Pred, Proj1, Proj2>
      constexpr bool contains_subrange(R1&& r1, R2&& r2,
                                       Pred pred = {}, Proj1 proj1 = {},
                                       Proj2 proj2 = {});
  }
  // for each
  template<class InputIter, class Function>
    constexpr Function for_each(InputIter first, InputIter last, Function f);
  template<class ExecutionPolicy, class ForwardIter, class Function>
    void for_each(ExecutionPolicy&& exec, // freestanding-deleted
                  ForwardIter first, ForwardIter last, Function f);
  namespace ranges {
    template<class I, class F>
      using for_each_result = in_fun_result<I, F>;
    template<input_iterator I, sentinel_for<I> S, class Proj = identity,
             indirectly_unary_invocable<projected<I, Proj>> Fun>
      constexpr for_each_result<I, Fun>
        for_each(I first, S last, Fun f, Proj proj = {});
    template<input_range R, class Proj = identity,
             indirectly_unary_invocable<projected<iterator_t<R>, Proj>> Fun>
      constexpr for_each_result<borrowed_iterator_t<R>, Fun>
        for_each(R&& r, Fun f, Proj proj = {});
  }
  template<class InputIter, class Size, class Function>
    constexpr InputIter for_each_n(InputIter first, Size n, Function f);
  template<class ExecutionPolicy, class ForwardIter, class Size, class Function>
    ForwardIter for_each_n(ExecutionPolicy&& exec, // freestanding-deleted
                           ForwardIter first, Size n, Function f);
  namespace ranges {
    template<class I, class F>
      using for_each_n_result = in_fun_result<I, F>;
    template<input_iterator I, class Proj = identity,
             indirectly_unary_invocable<projected<I, Proj>> Fun>
      constexpr for_each_n_result<I, Fun>
        for_each_n(I first, iter_difference_t<I> n, Fun f, Proj proj = {});
  }
  // find
  template<class InputIter, class T = typename iterator_traits<InputIter>::value_type>
    constexpr InputIter find(InputIter first, InputIter last, const T& value);
  template<class ExecutionPolicy, class ForwardIter,
           class T = typename iterator_traits<InputIter>::value_type>
    ForwardIter find(ExecutionPolicy&& exec, // freestanding-deleted
                     ForwardIter first, ForwardIter last, const T& value);
  template<class InputIter, class Pred>
    constexpr InputIter find_if(InputIter first, InputIter last, Pred pred);
  template<class ExecutionPolicy, class ForwardIter, class Pred>
    ForwardIter find_if(ExecutionPolicy&& exec, // freestanding-deleted
                        ForwardIter first, ForwardIter last, Pred pred);
  template<class InputIter, class Pred>
    constexpr InputIter find_if_not(InputIter first, InputIter last, Pred pred);
  template<class ExecutionPolicy, class ForwardIter, class Pred>
    ForwardIter find_if_not(ExecutionPolicy&& exec, // freestanding-deleted
                            ForwardIter first, ForwardIter last, Pred pred);
  namespace ranges {
    template<input_iterator I, sentinel_for<I> S, class Proj = identity
             class T = projected_value_t<I, Proj>>
      requires indirect_binary_predicate<ranges::equal_to, projected<I, Proj>, const T*>
      constexpr I find(I first, S last, const T& value, Proj proj = {});
    template<input_range R, class Proj = identity,
             class T = projected_value_t<iterator_t<R>, Proj>>
      requires indirect_binary_predicate<ranges::equal_to,
                                         projected<iterator_t<R>, Proj>, const T*>
      constexpr borrowed_iterator_t<R>
        find(R&& r, const T& value, Proj proj = {});
    template<input_iterator I, sentinel_for<I> S, class Proj = identity,
             indirect_unary_predicate<projected<I, Proj>> Pred>
      constexpr I find_if(I first, S last, Pred pred, Proj proj = {});
    template<input_range R, class Proj = identity,
             indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
      constexpr borrowed_iterator_t<R>
        find_if(R&& r, Pred pred, Proj proj = {});
    template<input_iterator I, sentinel_for<I> S, class Proj = identity,
             indirect_unary_predicate<projected<I, Proj>> Pred>
      constexpr I find_if_not(I first, S last, Pred pred, Proj proj = {});
    template<input_range R, class Proj = identity,
             indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
      constexpr borrowed_iterator_t<R>
        find_if_not(R&& r, Pred pred, Proj proj = {});
  }
  // find last
  namespace ranges {
    template<forward_iterator I, sentinel_for<I> S, class T, class Proj = identity>
      requires indirect_binary_predicate<ranges::equal_to, projected<I, Proj>, const T*>
      constexpr subrange<I> find_last(I first, S last, const T& value, Proj proj = {});
    template<forward_range R, class T, class Proj = identity>
      requires
        indirect_binary_predicate<ranges::equal_to,
            projected<iterator_t<R>, Proj>, const T*>
      constexpr borrowed_subrange_t<R> find_last(R&& r, const T& value, Proj proj = {});
    template<forward_iterator I, sentinel_for<I> S, class Proj = identity,
             indirect_unary_predicate<projected<I, Proj>> Pred>
      constexpr subrange<I> find_last_if(I first, S last, Pred pred, Proj proj = {});
    template<forward_range R, class Proj = identity,
             indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
      constexpr borrowed_subrange_t<R> find_last_if(R&& r, Pred pred, Proj proj = {});
    template<forward_iterator I, sentinel_for<I> S, class Proj = identity,
             indirect_unary_predicate<projected<I, Proj>> Pred>
      constexpr subrange<I> find_last_if_not(I first, S last, Pred pred, Proj proj = {});
    template<forward_range R, class Proj = identity,
             indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
      constexpr borrowed_subrange_t<R> find_last_if_not(R&& r, Pred pred, Proj proj = {});
  }
  // find end
  template<class ForwardIter1, class ForwardIter2>
    constexpr ForwardIter1
      find_end(ForwardIter1 first1, ForwardIter1 last1,
               ForwardIter2 first2, ForwardIter2 last2);
  template<class ForwardIter1, class ForwardIter2, class BinaryPred>
    constexpr ForwardIter1
      find_end(ForwardIter1 first1, ForwardIter1 last1,
               ForwardIter2 first2, ForwardIter2 last2,
               BinaryPred pred);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2>
    ForwardIter1
      find_end(ExecutionPolicy&& exec, // freestanding-deleted
               ForwardIter1 first1, ForwardIter1 last1,
               ForwardIter2 first2, ForwardIter2 last2);
  template<class ExecutionPolicy, class ForwardIter1,
           class ForwardIter2, class BinaryPred>
    ForwardIter1
      find_end(ExecutionPolicy&& exec, // freestanding-deleted
               ForwardIter1 first1, ForwardIter1 last1,
               ForwardIter2 first2, ForwardIter2 last2,
               BinaryPred pred);
  namespace ranges {
    template<forward_iterator I1, sentinel_for<I1> S1, forward_iterator I2,
             sentinel_for<I2> S2, class Pred = ranges::equal_to,
             class Proj1 = identity, class Proj2 = identity>
      requires indirectly_comparable<I1, I2, Pred, Proj1, Proj2>
      constexpr subrange<I1>
        find_end(I1 first1, S1 last1, I2 first2, S2 last2, Pred pred = {},
                 Proj1 proj1 = {}, Proj2 proj2 = {});
    template<forward_range R1, forward_range R2, class Pred = ranges::equal_to,
             class Proj1 = identity, class Proj2 = identity>
      requires indirectly_comparable<iterator_t<R1>, iterator_t<R2>, Pred, Proj1, Proj2>
      constexpr borrowed_subrange_t<R1>
        find_end(R1&& r1, R2&& r2, Pred pred = {},
                 Proj1 proj1 = {}, Proj2 proj2 = {});
  }
  // find first
  template<class InputIter, class ForwardIter>
    constexpr InputIter
      find_first_of(InputIter first1, InputIter last1,
                    ForwardIter first2, ForwardIter last2);
  template<class InputIter, class ForwardIter, class BinaryPred>
    constexpr InputIter
      find_first_of(InputIter first1, InputIter last1,
                    ForwardIter first2, ForwardIter last2,
                    BinaryPred pred);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2>
    ForwardIter1
      find_first_of(ExecutionPolicy&& exec, // freestanding-deleted
                    ForwardIter1 first1, ForwardIter1 last1,
                    ForwardIter2 first2, ForwardIter2 last2);
  template<class ExecutionPolicy, class ForwardIter1,
           class ForwardIter2, class BinaryPred>
    ForwardIter1
      find_first_of(ExecutionPolicy&& exec, // freestanding-deleted
                    ForwardIter1 first1, ForwardIter1 last1,
                    ForwardIter2 first2, ForwardIter2 last2,
                    BinaryPred pred);
  namespace ranges {
    template<input_iterator I1, sentinel_for<I1> S1, forward_iterator I2,
             sentinel_for<I2> S2, class Pred = ranges::equal_to,
             class Proj1 = identity, class Proj2 = identity>
      requires indirectly_comparable<I1, I2, Pred, Proj1, Proj2>
      constexpr I1 find_first_of(I1 first1, S1 last1, I2 first2, S2 last2, Pred pred = {},
                                 Proj1 proj1 = {}, Proj2 proj2 = {});
    template<input_range R1, forward_range R2, class Pred = ranges::equal_to,
             class Proj1 = identity, class Proj2 = identity>
      requires indirectly_comparable<iterator_t<R1>, iterator_t<R2>, Pred, Proj1, Proj2>
      constexpr borrowed_iterator_t<R1>
        find_first_of(R1&& r1, R2&& r2, Pred pred = {},
                      Proj1 proj1 = {}, Proj2 proj2 = {});
  }
  // adjacent find
  template<class ForwardIter>
    constexpr ForwardIter adjacent_find(ForwardIter first, ForwardIter last);
  template<class ForwardIter, class BinaryPred>
    constexpr ForwardIter adjacent_find(ForwardIter first, ForwardIter last,
                                        BinaryPred pred);
  template<class ExecutionPolicy, class ForwardIter>
    ForwardIter adjacent_find(ExecutionPolicy&& exec, // freestanding-deleted
                              ForwardIter first, ForwardIter last);
  template<class ExecutionPolicy, class ForwardIter, class BinaryPred>
    ForwardIter adjacent_find(ExecutionPolicy&& exec, // freestanding-deleted
                              ForwardIter first, ForwardIter last, BinaryPred pred);
  namespace ranges {
    template<forward_iterator I, sentinel_for<I> S, class Proj = identity,
             indirect_binary_predicate<projected<I, Proj>,
                                       projected<I, Proj>> Pred = ranges::equal_to>
      constexpr I adjacent_find(I first, S last, Pred pred = {}, Proj proj = {});
    template<forward_range R, class Proj = identity,
             indirect_binary_predicate<projected<iterator_t<R>, Proj>,
                                       projected<iterator_t<R>, Proj>>
                                         Pred = ranges::equal_to>
      constexpr borrowed_iterator_t<R>
        adjacent_find(R&& r, Pred pred = {}, Proj proj = {});
  }
  // count
  template<class InputIter, class T = typename iterator_traits<InputIter>::value_type>
    constexpr typename iterator_traits<InputIter>::difference_type
      count(InputIter first, InputIter last, const T& value);
  template<class ExecutionPolicy, class ForwardIter,
           class T = typename iterator_traits<InputIterator>::value_type>
    typename iterator_traits<ForwardIter>::difference_type
      count(ExecutionPolicy&& exec, // freestanding-deleted
            ForwardIter first, ForwardIter last, const T& value);
  template<class InputIter, class Pred>
    constexpr typename iterator_traits<InputIter>::difference_type
      count_if(InputIter first, InputIter last, Pred pred);
  template<class ExecutionPolicy, class ForwardIter, class Pred>
    typename iterator_traits<ForwardIter>::difference_type
      count_if(ExecutionPolicy&& exec, // freestanding-deleted
               ForwardIter first, ForwardIter last, Pred pred);
  namespace ranges {
    template<input_iterator I, sentinel_for<I> S, class Proj = identity,
             class T = projected_value_t<I, Proj>>
      requires indirect_binary_predicate<ranges::equal_to, projected<I, Proj>, const T*>
      constexpr iter_difference_t<I>
        count(I first, S last, const T& value, Proj proj = {});
    template<input_range R, class Proj = identity,
             class T = projected_value_t<iterator_t<R>, Proj>>
      requires indirect_binary_predicate<ranges::equal_to,
                                         projected<iterator_t<R>, Proj>, const T*>
      constexpr range_difference_t<R>
        count(R&& r, const T& value, Proj proj = {});
    template<input_iterator I, sentinel_for<I> S, class Proj = identity,
             indirect_unary_predicate<projected<I, Proj>> Pred>
      constexpr iter_difference_t<I>
        count_if(I first, S last, Pred pred, Proj proj = {});
    template<input_range R, class Proj = identity,
             indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
      constexpr range_difference_t<R>
        count_if(R&& r, Pred pred, Proj proj = {});
  }
  // mismatch
  template<class InputIter1, class InputIter2>
    constexpr pair<InputIter1, InputIter2>
      mismatch(InputIter1 first1, InputIter1 last1,
               InputIter2 first2);
  template<class InputIter1, class InputIter2, class BinaryPred>
    constexpr pair<InputIter1, InputIter2>
      mismatch(InputIter1 first1, InputIter1 last1,
               InputIter2 first2, BinaryPred pred);
  template<class InputIter1, class InputIter2>
    constexpr pair<InputIter1, InputIter2>
      mismatch(InputIter1 first1, InputIter1 last1,
               InputIter2 first2, InputIter2 last2);
  template<class InputIter1, class InputIter2, class BinaryPred>
    constexpr pair<InputIter1, InputIter2>
      mismatch(InputIter1 first1, InputIter1 last1,
               InputIter2 first2, InputIter2 last2,
               BinaryPred pred);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2>
    pair<ForwardIter1, ForwardIter2>
      mismatch(ExecutionPolicy&& exec, // freestanding-deleted
               ForwardIter1 first1, ForwardIter1 last1,
               ForwardIter2 first2);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class BinaryPred>
    pair<ForwardIter1, ForwardIter2>
      mismatch(ExecutionPolicy&& exec, // freestanding-deleted
               ForwardIter1 first1, ForwardIter1 last1,
               ForwardIter2 first2, BinaryPred pred);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2>
    pair<ForwardIter1, ForwardIter2>
      mismatch(ExecutionPolicy&& exec, // freestanding-deleted
               ForwardIter1 first1, ForwardIter1 last1,
               ForwardIter2 first2, ForwardIter2 last2);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class BinaryPred>
    pair<ForwardIter1, ForwardIter2>
      mismatch(ExecutionPolicy&& exec, // freestanding-deleted
               ForwardIter1 first1, ForwardIter1 last1,
               ForwardIter2 first2, ForwardIter2 last2,
               BinaryPred pred);
  namespace ranges {
    template<class I1, class I2>
      using mismatch_result = in_in_result<I1, I2>;
    template<input_iterator I1, sentinel_for<I1> S1, input_iterator I2,
             sentinel_for<I2> S2, class Pred = ranges::equal_to, class Proj1 = identity,
             class Proj2 = identity>
      requires indirectly_comparable<I1, I2, Pred, Proj1, Proj2>
      constexpr mismatch_result<I1, I2>
        mismatch(I1 first1, S1 last1, I2 first2, S2 last2, Pred pred = {},
                 Proj1 proj1 = {}, Proj2 proj2 = {});
    template<input_range R1, input_range R2,
             class Pred = ranges::equal_to, class Proj1 = identity,
             class Proj2 = identity>
      requires indirectly_comparable<iterator_t<R1>, iterator_t<R2>, Pred, Proj1, Proj2>
      constexpr mismatch_result<borrowed_iterator_t<R1>, borrowed_iterator_t<R2>>
        mismatch(R1&& r1, R2&& r2, Pred pred = {},
                 Proj1 proj1 = {}, Proj2 proj2 = {});
  }
  // equal
  template<class InputIter1, class InputIter2>
    constexpr bool equal(InputIter1 first1, InputIter1 last1,
                         InputIter2 first2);
  template<class InputIter1, class InputIter2, class BinaryPred>
    constexpr bool equal(InputIter1 first1, InputIter1 last1,
                         InputIter2 first2, BinaryPred pred);
  template<class InputIter1, class InputIter2>
    constexpr bool equal(InputIter1 first1, InputIter1 last1,
                         InputIter2 first2, InputIter2 last2);
  template<class InputIter1, class InputIter2, class BinaryPred>
    constexpr bool equal(InputIter1 first1, InputIter1 last1,
                         InputIter2 first2, InputIter2 last2,
                         BinaryPred pred);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2>
    bool equal(ExecutionPolicy&& exec, // freestanding-deleted
               ForwardIter1 first1, ForwardIter1 last1,
               ForwardIter2 first2);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class BinaryPred>
    bool equal(ExecutionPolicy&& exec, // freestanding-deleted
               ForwardIter1 first1, ForwardIter1 last1,
               ForwardIter2 first2, BinaryPred pred);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2>
    bool equal(ExecutionPolicy&& exec, // freestanding-deleted
               ForwardIter1 first1, ForwardIter1 last1,
               ForwardIter2 first2, ForwardIter2 last2);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class BinaryPred>
    bool equal(ExecutionPolicy&& exec, // freestanding-deleted
               ForwardIter1 first1, ForwardIter1 last1,
               ForwardIter2 first2, ForwardIter2 last2,
               BinaryPred pred);
  namespace ranges {
    template<input_iterator I1, sentinel_for<I1> S1, input_iterator I2,
             sentinel_for<I2> S2, class Pred = ranges::equal_to, class Proj1 = identity,
             class Proj2 = identity>
      requires indirectly_comparable<I1, I2, Pred, Proj1, Proj2>
      constexpr bool equal(I1 first1, S1 last1, I2 first2, S2 last2,
                           Pred pred = {},
                           Proj1 proj1 = {}, Proj2 proj2 = {});
    template<input_range R1, input_range R2, class Pred = ranges::equal_to,
             class Proj1 = identity, class Proj2 = identity>
      requires indirectly_comparable<iterator_t<R1>, iterator_t<R2>, Pred, Proj1, Proj2>
      constexpr bool equal(R1&& r1, R2&& r2, Pred pred = {},
                           Proj1 proj1 = {}, Proj2 proj2 = {});
  }
  // is permutation
  template<class ForwardIter1, class ForwardIter2>
    constexpr bool is_permutation(ForwardIter1 first1, ForwardIter1 last1,
                                  ForwardIter2 first2);
  template<class ForwardIter1, class ForwardIter2, class BinaryPred>
    constexpr bool is_permutation(ForwardIter1 first1, ForwardIter1 last1,
                                  ForwardIter2 first2, BinaryPred pred);
  template<class ForwardIter1, class ForwardIter2>
    constexpr bool is_permutation(ForwardIter1 first1, ForwardIter1 last1,
                                  ForwardIter2 first2, ForwardIter2 last2);
  template<class ForwardIter1, class ForwardIter2, class BinaryPred>
    constexpr bool is_permutation(ForwardIter1 first1, ForwardIter1 last1,
                                  ForwardIter2 first2, ForwardIter2 last2,
                                  BinaryPred pred);
  namespace ranges {
    template<forward_iterator I1, sentinel_for<I1> S1, forward_iterator I2,
             sentinel_for<I2> S2, class Proj1 = identity, class Proj2 = identity,
             indirect_equivalence_relation<projected<I1, Proj1>,
                                           projected<I2, Proj2>> Pred = ranges::equal_to>
      constexpr bool is_permutation(I1 first1, S1 last1, I2 first2, S2 last2,
                                    Pred pred = {},
                                    Proj1 proj1 = {}, Proj2 proj2 = {});
    template<forward_range R1, forward_range R2,
             class Proj1 = identity, class Proj2 = identity,
             indirect_equivalence_relation<projected<iterator_t<R1>, Proj1>,
                                           projected<iterator_t<R2>, Proj2>>
                                           Pred = ranges::equal_to>
      constexpr bool is_permutation(R1&& r1, R2&& r2, Pred pred = {},
                                    Proj1 proj1 = {}, Proj2 proj2 = {});
  }
  // search
  template<class ForwardIter1, class ForwardIter2>
    constexpr ForwardIter1
      search(ForwardIter1 first1, ForwardIter1 last1,
             ForwardIter2 first2, ForwardIter2 last2);
  template<class ForwardIter1, class ForwardIter2, class BinaryPred>
    constexpr ForwardIter1
      search(ForwardIter1 first1, ForwardIter1 last1,
             ForwardIter2 first2, ForwardIter2 last2, BinaryPred pred);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2>
    ForwardIter1
      search(ExecutionPolicy&& exec, // freestanding-deleted
             ForwardIter1 first1, ForwardIter1 last1,
             ForwardIter2 first2, ForwardIter2 last2);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class BinaryPred>
    ForwardIter1
      search(ExecutionPolicy&& exec, // freestanding-deleted
             ForwardIter1 first1, ForwardIter1 last1,
             ForwardIter2 first2, ForwardIter2 last2, BinaryPred pred);
  namespace ranges {
    template<forward_iterator I1, sentinel_for<I1> S1, forward_iterator I2,
             sentinel_for<I2> S2, class Pred = ranges::equal_to,
             class Proj1 = identity, class Proj2 = identity>
      requires indirectly_comparable<I1, I2, Pred, Proj1, Proj2>
      constexpr subrange<I1>
        search(I1 first1, S1 last1, I2 first2, S2 last2, Pred pred = {},
               Proj1 proj1 = {}, Proj2 proj2 = {});
    template<forward_range R1, forward_range R2, class Pred = ranges::equal_to,
             class Proj1 = identity, class Proj2 = identity>
      requires indirectly_comparable<iterator_t<R1>, iterator_t<R2>, Pred, Proj1, Proj2>
      constexpr borrowed_subrange_t<R1>
        search(R1&& r1, R2&& r2, Pred pred = {},
               Proj1 proj1 = {}, Proj2 proj2 = {});
  }
  template<class ForwardIter, class Size,
           class T = typename iterator_traits<ForwardIter>::value_type>
    constexpr ForwardIter
      search_n(ForwardIter first, ForwardIter last,
               Size count, const T& value);
  template<class ForwardIter, class Size,
           class T = typename iterator_traits<ForwardIter>::value_type, class BinaryPred>
    constexpr ForwardIter
      search_n(ForwardIter first, ForwardIter last,
               Size count, const T& value, BinaryPred pred);
  template<class ExecutionPolicy, class ForwardIter, class Size,
           class T = typename iterator_traits<ForwardIter>::value_type>
    ForwardIter
      search_n(ExecutionPolicy&& exec, // freestanding-deleted
               ForwardIter first, ForwardIter last,
               Size count, const T& value);
  template<class ExecutionPolicy, class ForwardIter, class Size,
           class T = typename iterator_traits<ForwardIter>::value_type, class BinaryPred>
    ForwardIter
      search_n(ExecutionPolicy&& exec, // freestanding-deleted
               ForwardIter first, ForwardIter last,
               Size count, const T& value, BinaryPred pred);
  namespace ranges {
    template<forward_iterator I, sentinel_for<I> S,
             class Pred = ranges::equal_to, class Proj = identity,
             class T = projected_value_t<I, Proj>>
      requires indirectly_comparable<I, const T*, Pred, Proj>
      constexpr subrange<I>
        search_n(I first, S last, iter_difference_t<I> count,
                 const T& value, Pred pred = {}, Proj proj = {});
    template<forward_range R, class Pred = ranges::equal_to, class Proj = identity,
             projected_value_t<iterator_t<R>, Proj>>
      requires indirectly_comparable<iterator_t<R>, const T*, Pred, Proj>
      constexpr borrowed_subrange_t<R>
        search_n(R&& r, range_difference_t<R> count,
                 const T& value, Pred pred = {}, Proj proj = {});
  }
  template<class ForwardIter, class Searcher>
    constexpr ForwardIter
      search(ForwardIter first, ForwardIter last, const Searcher& searcher);
  namespace ranges {
    // starts with
    template<input_iterator I1, sentinel_for<I1> S1, input_iterator I2,
             sentinel_for<I2> S2, class Pred = ranges::equal_to,
             class Proj1 = identity, class Proj2 = identity>
      requires indirectly_comparable<I1, I2, Pred, Proj1, Proj2>
      constexpr bool starts_with(I1 first1, S1 last1, I2 first2, S2 last2, Pred pred = {},
                                 Proj1 proj1 = {}, Proj2 proj2 = {});
    template<input_range R1, input_range R2, class Pred = ranges::equal_to,
             class Proj1 = identity, class Proj2 = identity>
      requires indirectly_comparable<iterator_t<R1>, iterator_t<R2>, Pred, Proj1, Proj2>
      constexpr bool starts_with(R1&& r1, R2&& r2, Pred pred = {},
                                 Proj1 proj1 = {}, Proj2 proj2 = {});
    // ends with
    template<input_iterator I1, sentinel_for<I1> S1, input_iterator I2,
             sentinel_for<I2> S2, class Pred = ranges::equal_to,
             class Proj1 = identity, class Proj2 = identity>
      requires (forward_iterator<I1> || sized_sentinel_for<S1, I1>) &&
               (forward_iterator<I2> || sized_sentinel_for<S2, I2>) &&
               indirectly_comparable<I1, I2, Pred, Proj1, Proj2>
      constexpr bool ends_with(I1 first1, S1 last1, I2 first2, S2 last2, Pred pred = {},
                               Proj1 proj1 = {}, Proj2 proj2 = {});
    template<input_range R1, input_range R2, class Pred = ranges::equal_to,
             class Proj1 = identity, class Proj2 = identity>
      requires (forward_range<R1> || sized_range<R1>) &&
               (forward_range<R2> || sized_range<R2>) &&
               indirectly_comparable<iterator_t<R1>, iterator_t<R2>, Pred, Proj1, Proj2>
      constexpr bool ends_with(R1&& r1, R2&& r2, Pred pred = {},
                               Proj1 proj1 = {}, Proj2 proj2 = {});
    // fold
    template<class F>
    class /* flipped */ {   // exposition only
      F f;                  // exposition only
    public:
      template<class T, class U> requires invocable<F&, U, T>
      invoke_result_t<F&, U, T> operator()(T&&, U&&);
    };
    template<class F, class T, class I, class U>
      concept /* indirectly-binary-left-foldable-impl */ =  // exposition only
        movable<T> && movable<U> &&
        convertible_to<T, U> && invocable<F&, U, iter_reference_t<I>> &&
        assignable_from<U&, invoke_result_t<F&, U, iter_reference_t<I>>>;
    template<class F, class T, class I>
      concept /* indirectly-binary-left-foldable */ =       // exposition only
        copy_constructible<F> && indirectly_readable<I> &&
        invocable<F&, T, iter_reference_t<I>> &&
        convertible_to<invoke_result_t<F&, T, iter_reference_t<I>>,
               decay_t<invoke_result_t<F&, T, iter_reference_t<I>>>> &&
        /* indirectly-binary-left-foldable-impl */
             <F, T, I, decay_t<invoke_result_t<F&, T, iter_reference_t<I>>>>;
    template<class F, class T, class I>
      concept /* indirectly-binary-right-foldable */ =      // exposition only
        /* indirectly-binary-left-foldable */</* flipped */<F>, T, I>;
    template<input_iterator I, sentinel_for<I> S, class T = iter_value_t<I>,
             /* indirectly-binary-left-foldable */<T, I> F>
      constexpr auto fold_left(I first, S last, T init, F f);
    template<input_range R, class T = range_value_t<R>,
             /* indirectly-binary-left-foldable */<T, iterator_t<R>> F>
      constexpr auto fold_left(R&& r, T init, F f);
    template<input_iterator I, sentinel_for<I> S,
             /* indirectly-binary-left-foldable */<iter_value_t<I>, I> F>
      requires constructible_from<iter_value_t<I>, iter_reference_t<I>>
      constexpr auto fold_left_first(I first, S last, F f);
    template<input_range R,
             /* indirectly-binary-left-foldable */<range_value_t<R>, iterator_t<R>> F>
      requires constructible_from<range_value_t<R>, range_reference_t<R>>
      constexpr auto fold_left_first(R&& r, F f);
    template<bidirectional_iterator I, sentinel_for<I> S, class T = iter_value_t<I>,
             /* indirectly-binary-right-foldable */<T, I> F>
      constexpr auto fold_right(I first, S last, T init, F f);
    template<bidirectional_range R, class T = range_value_t<R>,
             /* indirectly-binary-right-foldable */<T, iterator_t<R>> F>
      constexpr auto fold_right(R&& r, T init, F f);
    template<bidirectional_iterator I, sentinel_for<I> S,
             /* indirectly-binary-right-foldable */<iter_value_t<I>, I> F>
      requires constructible_from<iter_value_t<I>, iter_reference_t<I>>
    constexpr auto fold_right_last(I first, S last, F f);
    template<bidirectional_range R,
             /* indirectly-binary-right-foldable */<range_value_t<R>, iterator_t<R>> F>
      requires constructible_from<range_value_t<R>, range_reference_t<R>>
      constexpr auto fold_right_last(R&& r, F f);
    template<class I, class T>
      using fold_left_with_iter_result = in_value_result<I, T>;
    template<class I, class T>
      using fold_left_first_with_iter_result = in_value_result<I, T>;
    template<input_iterator I, sentinel_for<I> S, class T = iter_value_t<I>,
             /* indirectly-binary-left-foldable */<T, I> F>
      constexpr /* see description */ fold_left_with_iter(I first, S last, T init, F f);
    template<input_range R, class T = range_value_t<R>,
             /* indirectly-binary-left-foldable */<T, iterator_t<R>> F>
      constexpr /* see description */ fold_left_with_iter(R&& r, T init, F f);
    template<input_iterator I, sentinel_for<I> S,
             /* indirectly-binary-left-foldable */<iter_value_t<I>, I> F>
      requires constructible_from<iter_value_t<I>, iter_reference_t<I>>
      constexpr /* see description */ fold_left_first_with_iter(I first, S last, F f);
    template<input_range R,
             /* indirectly-binary-left-foldable */<range_value_t<R>, iterator_t<R>> F>
      requires constructible_from<range_value_t<R>, range_reference_t<R>>
      constexpr /* see description */ fold_left_first_with_iter(R&& r, F f);
  }
  // mutating sequence operations
  // copy
  template<class InputIter, class OutputIter>
    constexpr OutputIter copy(InputIter first, InputIter last,
                              OutputIter result);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2>
    ForwardIter2 copy(ExecutionPolicy&& exec, // freestanding-deleted
                      ForwardIter1 first, ForwardIter1 last,
                      ForwardIter2 result);
  namespace ranges {
    template<class I, class O>
      using copy_result = in_out_result<I, O>;
    template<input_iterator I, sentinel_for<I> S, weakly_incrementable O>
      requires indirectly_copyable<I, O>
      constexpr copy_result<I, O> copy(I first, S last, O result);
    template<input_range R, weakly_incrementable O>
      requires indirectly_copyable<iterator_t<R>, O>
      constexpr copy_result<borrowed_iterator_t<R>, O> copy(R&& r, O result);
  }
  template<class InputIter, class Size, class OutputIter>
    constexpr OutputIter copy_n(InputIter first, Size n, OutputIter result);
  template<class ExecutionPolicy,
           class ForwardIter1, class Size, class ForwardIter2>
    ForwardIter2 copy_n(ExecutionPolicy&& exec, // freestanding-deleted
                        ForwardIter1 first, Size n, ForwardIter2 result);
  namespace ranges {
    template<class I, class O>
      using copy_n_result = in_out_result<I, O>;
    template<input_iterator I, weakly_incrementable O>
      requires indirectly_copyable<I, O>
      constexpr copy_n_result<I, O> copy_n(I first, iter_difference_t<I> n, O result);
  }
  template<class InputIter, class OutputIter, class Pred>
    constexpr OutputIter copy_if(InputIter first, InputIter last,
                                 OutputIter result, Pred pred);
  template<class ExecutionPolicy,
           class ForwardIter1, class ForwardIter2, class Pred>
    ForwardIter2 copy_if(ExecutionPolicy&& exec, // freestanding-deleted
                         ForwardIter1 first, ForwardIter1 last,
                         ForwardIter2 result, Pred pred);
  namespace ranges {
    template<class I, class O>
      using copy_if_result = in_out_result<I, O>;
    template<input_iterator I, sentinel_for<I> S, weakly_incrementable O,
             class Proj = identity, indirect_unary_predicate<projected<I, Proj>> Pred>
      requires indirectly_copyable<I, O>
      constexpr copy_if_result<I, O>
        copy_if(I first, S last, O result, Pred pred, Proj proj = {});
    template<input_range R, weakly_incrementable O, class Proj = identity,
             indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
      requires indirectly_copyable<iterator_t<R>, O>
      constexpr copy_if_result<borrowed_iterator_t<R>, O>
        copy_if(R&& r, O result, Pred pred, Proj proj = {});
  }
  template<class BidirectionalIter1, class BidirectionalIter2>
    constexpr BidirectionalIter2
      copy_backward(BidirectionalIter1 first, BidirectionalIter1 last,
                    BidirectionalIter2 result);
  namespace ranges {
    template<class I1, class I2>
      using copy_backward_result = in_out_result<I1, I2>;
    template<bidirectional_iterator I1, sentinel_for<I1> S1, bidirectional_iterator I2>
      requires indirectly_copyable<I1, I2>
      constexpr copy_backward_result<I1, I2>
        copy_backward(I1 first, S1 last, I2 result);
    template<bidirectional_range R, bidirectional_iterator I>
      requires indirectly_copyable<iterator_t<R>, I>
      constexpr copy_backward_result<borrowed_iterator_t<R>, I>
        copy_backward(R&& r, I result);
  }
  // move
  template<class InputIter, class OutputIter>
    constexpr OutputIter move(InputIter first, InputIter last, OutputIter result);
  template<class ExecutionPolicy, class ForwardIter1,
           class ForwardIter2>
    ForwardIter2 move(ExecutionPolicy&& exec, // freestanding-deleted
                      ForwardIter1 first, ForwardIter1 last, ForwardIter2 result);
  namespace ranges {
    template<class I, class O>
      using move_result = in_out_result<I, O>;
    template<input_iterator I, sentinel_for<I> S, weakly_incrementable O>
      requires indirectly_movable<I, O>
      constexpr move_result<I, O> move(I first, S last, O result);
    template<input_range R, weakly_incrementable O>
      requires indirectly_movable<iterator_t<R>, O>
      constexpr move_result<borrowed_iterator_t<R>, O> move(R&& r, O result);
  }
  template<class BidirectionalIter1, class BidirectionalIter2>
    constexpr BidirectionalIter2
      move_backward(BidirectionalIter1 first, BidirectionalIter1 last,
                    BidirectionalIter2 result);
  namespace ranges {
    template<class I1, class I2>
      using move_backward_result = in_out_result<I1, I2>;
    template<bidirectional_iterator I1, sentinel_for<I1> S1, bidirectional_iterator I2>
      requires indirectly_movable<I1, I2>
      constexpr move_backward_result<I1, I2>
        move_backward(I1 first, S1 last, I2 result);
    template<bidirectional_range R, bidirectional_iterator I>
      requires indirectly_movable<iterator_t<R>, I>
      constexpr move_backward_result<borrowed_iterator_t<R>, I>
        move_backward(R&& r, I result);
  }
  // swap
  template<class ForwardIter1, class ForwardIter2>
    constexpr ForwardIter2 swap_ranges(ForwardIter1 first1, ForwardIter1 last1,
                                       ForwardIter2 first2);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2>
    ForwardIter2 swap_ranges(ExecutionPolicy&& exec, // freestanding-deleted
                             ForwardIter1 first1, ForwardIter1 last1,
                             ForwardIter2 first2);
  namespace ranges {
    template<class I1, class I2>
      using swap_ranges_result = in_in_result<I1, I2>;
    template<input_iterator I1, sentinel_for<I1> S1,
             input_iterator I2, sentinel_for<I2> S2>
      requires indirectly_swappable<I1, I2>
      constexpr swap_ranges_result<I1, I2>
        swap_ranges(I1 first1, S1 last1, I2 first2, S2 last2);
    template<input_range R1, input_range R2>
      requires indirectly_swappable<iterator_t<R1>, iterator_t<R2>>
      constexpr swap_ranges_result<borrowed_iterator_t<R1>, borrowed_iterator_t<R2>>
        swap_ranges(R1&& r1, R2&& r2);
  }
  template<class ForwardIter1, class ForwardIter2>
    constexpr void iter_swap(ForwardIter1 a, ForwardIter2 b);
  // transform
  template<class InputIter, class OutputIter, class UnaryOperation>
    constexpr OutputIter
      transform(InputIter first1, InputIter last1,
                OutputIter result, UnaryOperation op);
  template<class InputIter1, class InputIter2, class OutputIter,
           class BinaryOperation>
    constexpr OutputIter
      transform(InputIter1 first1, InputIter1 last1,
                InputIter2 first2, OutputIter result,
                BinaryOperation binary_op);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class UnaryOperation>
    ForwardIter2
      transform(ExecutionPolicy&& exec, // freestanding-deleted
                ForwardIter1 first1, ForwardIter1 last1,
                ForwardIter2 result, UnaryOperation op);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class ForwardIter, class BinaryOperation>
    ForwardIter
      transform(ExecutionPolicy&& exec, // freestanding-deleted
                ForwardIter1 first1, ForwardIter1 last1,
                ForwardIter2 first2, ForwardIter result,
                BinaryOperation binary_op);
  namespace ranges {
    template<class I, class O>
      using unary_transform_result = in_out_result<I, O>;
    template<input_iterator I, sentinel_for<I> S, weakly_incrementable O,
             copy_constructible F, class Proj = identity>
      requires indirectly_writable<O, indirect_result_t<F&, projected<I, Proj>>>
      constexpr unary_transform_result<I, O>
        transform(I first1, S last1, O result, F op, Proj proj = {});
    template<input_range R, weakly_incrementable O,
             copy_constructible F, class Proj = identity>
      requires
        indirectly_writable<O, indirect_result_t<F&, projected<iterator_t<R>, Proj>>>
      constexpr unary_transform_result<borrowed_iterator_t<R>, O>
        transform(R&& r, O result, F op, Proj proj = {});
    template<class I1, class I2, class O>
      using binary_transform_result = in_in_out_result<I1, I2, O>;
    template<input_iterator I1, sentinel_for<I1> S1, input_iterator I2,
             sentinel_for<I2> S2, weakly_incrementable O, copy_constructible F,
             class Proj1 = identity, class Proj2 = identity>
      requires indirectly_writable<O, indirect_result_t<F&, projected<I1, Proj1>,
                                                        projected<I2, Proj2>>>
      constexpr binary_transform_result<I1, I2, O>
        transform(I1 first1, S1 last1, I2 first2, S2 last2, O result,
                  F binary_op, Proj1 proj1 = {}, Proj2 proj2 = {});
    template<input_range R1, input_range R2, weakly_incrementable O,
             copy_constructible F, class Proj1 = identity, class Proj2 = identity>
      requires indirectly_writable
                   <O, indirect_result_t<F&, projected<iterator_t<R1>, Proj1>, 
                                         projected<iterator_t<R2>, Proj2>>>
      constexpr binary_transform_result<borrowed_iterator_t<R1>,
                                        borrowed_iterator_t<R2>, O>
        transform(R1&& r1, R2&& r2, O result,
                  F binary_op, Proj1 proj1 = {}, Proj2 proj2 = {});
  }
  // replace
  template<class ForwardIter, class T = typename iterator_traits<ForwardIter>::value_type>
    constexpr void replace(ForwardIter first, ForwardIter last,
                           const T& old_value, const T& new_value);
  template<class ExecutionPolicy, class ForwardIter,
           class T = typename iterator_traits<ForwardIter>::value_type>
    void replace(ExecutionPolicy&& exec, // freestanding-deleted
                 ForwardIter first, ForwardIter last,
                 const T& old_value, const T& new_value);
  template<class ForwardIter, class Pred,
           class T = typename iterator_traits<ForwardIter>::value_type>
    constexpr void replace_if(ForwardIter first, ForwardIter last,
                              Pred pred, const T& new_value);
  template<class ExecutionPolicy, class ForwardIter, class Pred,
           class T = typename iterator_traits<ForwardIter>::value_type>
    void replace_if(ExecutionPolicy&& exec, // freestanding-deleted
                    ForwardIter first, ForwardIter last,
                    Pred pred, const T& new_value);
  namespace ranges {
    template<input_iterator I, sentinel_for<I> S,
             class Proj = identity, class T1 = projected_value_t<I, Proj>, class T2 = T1>
      requires indirectly_writable<I, const T2&> &&
               indirect_binary_predicate<ranges::equal_to, projected<I, Proj>, const T1*>
      constexpr I replace(I first, S last, const T1& old_value,
                          const T2& new_value, Proj proj = {});
    template<input_range R, class Proj = identity,
             class T1 = projected_value_t<iterator_t<R>, Proj>, class T2 = T1>
      requires indirectly_writable<iterator_t<R>, const T2&> &&
               indirect_binary_predicate<ranges::equal_to,
                                         projected<iterator_t<R>, Proj>, const T1*>
      constexpr borrowed_iterator_t<R> replace(R&& r, const T1& old_value,
                                               const T2& new_value, Proj proj = {});
    template<input_iterator I, sentinel_for<I> S, class Proj = identity,
             class T = projected_value_t<I, Proj>,
             indirect_unary_predicate<projected<I, Proj>> Pred>
      requires indirectly_writable<I, const T&>
      constexpr I replace_if(I first, S last, Pred pred,
                             const T& new_value, Proj proj = {});
    template<input_range R, class Proj = identity,
             class T = projected_value_t<iterator_t<R>, Proj>,
             indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
      requires indirectly_writable<iterator_t<R>, const T&>
      constexpr borrowed_iterator_t<R> replace_if(R&& r, Pred pred,
                                                  const T& new_value, Proj proj = {});
  }
  template<class InputIter, class OutputIter, class T>
    constexpr OutputIter replace_copy(InputIter first, InputIter last, OutputIter result,
                                      const T& old_value, const T& new_value);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2, class T>
    ForwardIter2 replace_copy(ExecutionPolicy&& exec, // freestanding-deleted
                              ForwardIter1 first, ForwardIter1 last, ForwardIter2 result,
                              const T& old_value, const T& new_value);
  template<class InputIter, class OutputIter, class Pred,
           class T = typename iterator_traits<OutputIter>::value_type>
    constexpr OutputIter replace_copy_if(InputIter first, InputIter last,
                                         OutputIter result,
                                         Pred pred, const T& new_value);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class Pred, class T = typename iterator_traits<ForwardIter2>::value_type>
    ForwardIter2 replace_copy_if(ExecutionPolicy&& exec, // freestanding-deleted
                                 ForwardIter1 first, ForwardIter1 last,
                                 ForwardIter2 result,
                                 Pred pred, const T& new_value);
  namespace ranges {
    template<class I, class O>
      using replace_copy_result = in_out_result<I, O>;
    template<input_iterator I, sentinel_for<I> S, class O, class Proj = identity,
             class T1 = projected_value_t<I, Proj>, class T2 = iter_value_t<O>>
      requires indirectly_copyable<I, O> &&
               indirect_binary_predicate<ranges::equal_to,
                                         projected<I, Proj>, const T1*> &&
               output_iterator<O, const T2&>
      constexpr replace_copy_result<I, O>
        replace_copy(I first, S last, O result, const T1& old_value,
                     const T2& new_value, Proj proj = {});
    template<input_range R, class O, class Proj = identity,
             class T1 = projected_value_t<iterator_t<R>, Proj>,
             class T2 = iter_value_t<O>>
      requires indirectly_copyable<iterator_t<R>, O> &&
               indirect_binary_predicate<ranges::equal_to,
                                         projected<iterator_t<R>, Proj>, const T1*> &&
               output_iterator<O, const T2&>
      constexpr replace_copy_result<borrowed_iterator_t<R>, O>
        replace_copy(R&& r, O result, const T1& old_value,
                     const T2& new_value, Proj proj = {});
    template<class I, class O>
      using replace_copy_if_result = in_out_result<I, O>;
    template<input_iterator I, sentinel_for<I> S, class O, class T = iter_value_t<O>,
             class Proj = identity, indirect_unary_predicate<projected<I, Proj>> Pred>
      requires indirectly_copyable<I, O> && output_iterator<O, const T&>
      constexpr replace_copy_if_result<I, O>
        replace_copy_if(I first, S last, O result, Pred pred,
                        const T& new_value, Proj proj = {});
    template<input_range R, class O, class T = iter_value_t<O>, class Proj = identity,
             indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
      requires indirectly_copyable<iterator_t<R>, O> && output_iterator<O, const T&>
      constexpr replace_copy_if_result<borrowed_iterator_t<R>, O>
        replace_copy_if(R&& r, O result, Pred pred,
                        const T& new_value, Proj proj = {});
  }
  // fill
  template<class ForwardIter, class T = typename iterator_traits<ForwardIter>::value_type>
    constexpr void fill(ForwardIter first, ForwardIter last, const T& value);
  template<class ExecutionPolicy, class ForwardIter,
           class T = typename iterator_traits<ForwardIter>::value_type>
    void fill(ExecutionPolicy&& exec, // freestanding-deleted
              ForwardIter first, ForwardIter last, const T& value);
  template<class OutputIter, class Size,
           class T = typename iterator_traits<OutputIter>::value_type>
    constexpr OutputIter fill_n(OutputIter first, Size n, const T& value);
  template<class ExecutionPolicy, class ForwardIter,
           class Size, class T = typename iterator_traits<OutputIter>::value_type>
    ForwardIter fill_n(ExecutionPolicy&& exec, // freestanding-deleted
                       ForwardIter first, Size n, const T& value);
  namespace ranges {
    template<class O, sentinel_for<O> S, class T = iter_value_t<O>>
      requires output_iterator<O, const T&>
      constexpr O fill(O first, S last, const T& value);
    template<class R, class T = range_value_t<R>>
      requires output_range<R, const T&>
      constexpr borrowed_iterator_t<R> fill(R&& r, const T& value);
    template<class O, class T = iter_value_t<O>>
      requires output_iterator<O, const T&>
      constexpr O fill_n(O first, iter_difference_t<O> n, const T& value);
  }
  // generate
  template<class ForwardIter, class Generator>
    constexpr void generate(ForwardIter first, ForwardIter last, Generator gen);
  template<class ExecutionPolicy, class ForwardIter, class Generator>
    void generate(ExecutionPolicy&& exec, // freestanding-deleted
                  ForwardIter first, ForwardIter last, Generator gen);
  template<class OutputIter, class Size, class Generator>
    constexpr OutputIter generate_n(OutputIter first, Size n, Generator gen);
  template<class ExecutionPolicy, class ForwardIter, class Size, class Generator>
    ForwardIter generate_n(ExecutionPolicy&& exec, // freestanding-deleted
                           ForwardIter first, Size n, Generator gen);
  namespace ranges {
    template<input_or_output_iterator O, sentinel_for<O> S, copy_constructible F>
      requires invocable<F&> && indirectly_writable<O, invoke_result_t<F&>>
      constexpr O generate(O first, S last, F gen);
    template<class R, copy_constructible F>
      requires invocable<F&> && output_range<R, invoke_result_t<F&>>
      constexpr borrowed_iterator_t<R> generate(R&& r, F gen);
    template<input_or_output_iterator O, copy_constructible F>
      requires invocable<F&> && indirectly_writable<O, invoke_result_t<F&>>
      constexpr O generate_n(O first, iter_difference_t<O> n, F gen);
  }
  // remove
  template<class ForwardIter, class T = typename iterator_traits<ForwardIter>::value_type>
    constexpr ForwardIter remove(ForwardIter first, ForwardIter last, const T& value);
  template<class ExecutionPolicy, class ForwardIter,
           class T = typename iterator_traits<ForwardIter>::value_type>
    ForwardIter remove(ExecutionPolicy&& exec, // freestanding-deleted
                       ForwardIter first, ForwardIter last, const T& value);
  template<class ForwardIter, class Pred>
    constexpr ForwardIter remove_if(ForwardIter first, ForwardIter last, Pred pred);
  template<class ExecutionPolicy, class ForwardIter, class Pred>
    ForwardIter remove_if(ExecutionPolicy&& exec, // freestanding-deleted
                          ForwardIter first, ForwardIter last, Pred pred);
  namespace ranges {
    template<permutable I, sentinel_for<I> S, class Proj = identity,
             class T = projected_value_t<I, Proj>>
      requires indirect_binary_predicate<ranges::equal_to, projected<I, Proj>, const T*>
      constexpr subrange<I> remove(I first, S last, const T& value, Proj proj = {});
    template<forward_range R, class Proj = identity,
             class T = projected_value_t<iterator_t<R>, Proj>>
      requires permutable<iterator_t<R>> &&
               indirect_binary_predicate<ranges::equal_to,
                                         projected<iterator_t<R>, Proj>, const T*>
      constexpr borrowed_subrange_t<R> remove(R&& r, const T& value, Proj proj = {});
    template<permutable I, sentinel_for<I> S, class Proj = identity,
             indirect_unary_predicate<projected<I, Proj>> Pred>
      constexpr subrange<I> remove_if(I first, S last, Pred pred, Proj proj = {});
    template<forward_range R, class Proj = identity,
             indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
      requires permutable<iterator_t<R>>
      constexpr borrowed_subrange_t<R> remove_if(R&& r, Pred pred, Proj proj = {});
  }
  template<class InputIter, class OutputIter,
           class T = typename iterator_traits<InputIter>::value_type>
    constexpr OutputIter remove_copy(InputIter first, InputIter last,
                                     OutputIter result, const T& value);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class T = typename iterator_traits<ForwardIter1>::value_type>
    ForwardIter2 remove_copy(ExecutionPolicy&& exec, // freestanding-deleted
                             ForwardIter1 first, ForwardIter1 last,
                             ForwardIter2 result, const T& value);
  template<class InputIter, class OutputIter, class Pred>
    constexpr OutputIter remove_copy_if(InputIter first, InputIter last,
                                        OutputIter result, Pred pred);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2, class Pred>
    ForwardIter2 remove_copy_if(ExecutionPolicy&& exec, // freestanding-deleted
                                ForwardIter1 first, ForwardIter1 last,
                                ForwardIter2 result, Pred pred);
  namespace ranges {
    template<class I, class O>
      using remove_copy_result = in_out_result<I, O>;
    template<input_iterator I, sentinel_for<I> S, weakly_incrementable O,
             class Proj = identity, class T = projected_value_t<I, Proj>>
      requires indirectly_copyable<I, O> &&
               indirect_binary_predicate<ranges::equal_to, projected<I, Proj>, const T*>
      constexpr remove_copy_result<I, O>
        remove_copy(I first, S last, O result, const T& value, Proj proj = {});
    template<input_range R, weakly_incrementable O, class Proj = identity,
             class T = projected_value_t<iterator_t<R>, Proj>>
      requires indirectly_copyable<iterator_t<R>, O> &&
               indirect_binary_predicate<ranges::equal_to,
                                         projected<iterator_t<R>, Proj>, const T*>
      constexpr remove_copy_result<borrowed_iterator_t<R>, O>
        remove_copy(R&& r, O result, const T& value, Proj proj = {});
    template<class I, class O>
      using remove_copy_if_result = in_out_result<I, O>;
    template<input_iterator I, sentinel_for<I> S, weakly_incrementable O,
             class Proj = identity, indirect_unary_predicate<projected<I, Proj>> Pred>
      requires indirectly_copyable<I, O>
      constexpr remove_copy_if_result<I, O>
        remove_copy_if(I first, S last, O result, Pred pred, Proj proj = {});
    template<input_range R, weakly_incrementable O, class Proj = identity,
             indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
      requires indirectly_copyable<iterator_t<R>, O>
      constexpr remove_copy_if_result<borrowed_iterator_t<R>, O>
        remove_copy_if(R&& r, O result, Pred pred, Proj proj = {});
  }
  // unique
  template<class ForwardIter>
    constexpr ForwardIter unique(ForwardIter first, ForwardIter last);
  template<class ForwardIter, class BinaryPred>
    constexpr ForwardIter unique(ForwardIter first, ForwardIter last, BinaryPred pred);
  template<class ExecutionPolicy, class ForwardIter>
    ForwardIter unique(ExecutionPolicy&& exec, // freestanding-deleted
                       ForwardIter first, ForwardIter last);
  template<class ExecutionPolicy, class ForwardIter, class BinaryPred>
    ForwardIter unique(ExecutionPolicy&& exec, // freestanding-deleted
                       ForwardIter first, ForwardIter last, BinaryPred pred);
  namespace ranges {
    template<permutable I, sentinel_for<I> S, class Proj = identity,
             indirect_equivalence_relation<projected<I, Proj>> C = ranges::equal_to>
      constexpr subrange<I> unique(I first, S last, C comp = {}, Proj proj = {});
    template<forward_range R, class Proj = identity,
             indirect_equivalence_relation
                 <projected<iterator_t<R>, Proj>> C = ranges::equal_to>
      requires permutable<iterator_t<R>>
      constexpr borrowed_subrange_t<R> unique(R&& r, C comp = {}, Proj proj = {});
  }
  template<class InputIter, class OutputIter>
    constexpr OutputIter unique_copy(InputIter first, InputIter last,
                                     OutputIter result);
  template<class InputIter, class OutputIter, class BinaryPred>
    constexpr OutputIter unique_copy(InputIter first, InputIter last,
                                     OutputIter result, BinaryPred pred);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2>
    ForwardIter2 unique_copy(ExecutionPolicy&& exec, // freestanding-deleted
                             ForwardIter1 first, ForwardIter1 last,
                             ForwardIter2 result);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class BinaryPred>
    ForwardIter2 unique_copy(ExecutionPolicy&& exec, // freestanding-deleted
                             ForwardIter1 first, ForwardIter1 last,
                             ForwardIter2 result, BinaryPred pred);
  namespace ranges {
    template<class I, class O>
      using unique_copy_result = in_out_result<I, O>;
    template<input_iterator I, sentinel_for<I> S,
             weakly_incrementable O, class Proj = identity,
             indirect_equivalence_relation<projected<I, Proj>> C = ranges::equal_to>
      requires indirectly_copyable<I, O> &&
               (forward_iterator<I> ||
                (input_iterator<O> && same_as<iter_value_t<I>, iter_value_t<O>>) ||
                indirectly_copyable_storable<I, O>)
      constexpr unique_copy_result<I, O>
        unique_copy(I first, S last, O result, C comp = {}, Proj proj = {});
    template<input_range R, weakly_incrementable O, class Proj = identity,
             indirect_equivalence_relation
                 <projected<iterator_t<R>, Proj>> C = ranges::equal_to>
      requires indirectly_copyable<iterator_t<R>, O> &&
               (forward_iterator<iterator_t<R>> ||
                (input_iterator<O> && same_as<range_value_t<R>, iter_value_t<O>>) ||
                indirectly_copyable_storable<iterator_t<R>, O>)
      constexpr unique_copy_result<borrowed_iterator_t<R>, O>
        unique_copy(R&& r, O result, C comp = {}, Proj proj = {});
  }
  // reverse
  template<class BidirectionalIter>
    constexpr void reverse(BidirectionalIter first, BidirectionalIter last);
  template<class ExecutionPolicy, class BidirectionalIter>
    void reverse(ExecutionPolicy&& exec, // freestanding-deleted
                 BidirectionalIter first, BidirectionalIter last);
  namespace ranges {
    template<bidirectional_iterator I, sentinel_for<I> S>
      requires permutable<I>
      constexpr I reverse(I first, S last);
    template<bidirectional_range R>
      requires permutable<iterator_t<R>>
      constexpr borrowed_iterator_t<R> reverse(R&& r);
  }
  template<class BidirectionalIter, class OutputIter>
    constexpr OutputIter reverse_copy(BidirectionalIter first, BidirectionalIter last,
                                      OutputIter result);
  template<class ExecutionPolicy, class BidirectionalIter, class ForwardIter>
    ForwardIter reverse_copy(ExecutionPolicy&& exec, // freestanding-deleted
                             BidirectionalIter first, BidirectionalIter last,
                             ForwardIter result);
  namespace ranges {
    template<class I, class O>
      using reverse_copy_result = in_out_result<I, O>;
    template<bidirectional_iterator I, sentinel_for<I> S, weakly_incrementable O>
      requires indirectly_copyable<I, O>
      constexpr reverse_copy_result<I, O>
        reverse_copy(I first, S last, O result);
    template<bidirectional_range R, weakly_incrementable O>
      requires indirectly_copyable<iterator_t<R>, O>
      constexpr reverse_copy_result<borrowed_iterator_t<R>, O>
        reverse_copy(R&& r, O result);
  }
  // rotate
  template<class ForwardIter>
    constexpr ForwardIter rotate(ForwardIter first, ForwardIter middle, ForwardIter last);
  template<class ExecutionPolicy, class ForwardIter>
    ForwardIter rotate(ExecutionPolicy&& exec, // freestanding-deleted
                       ForwardIter first, ForwardIter middle, ForwardIter last);
  namespace ranges {
    template<permutable I, sentinel_for<I> S>
      constexpr subrange<I> rotate(I first, I middle, S last);
    template<forward_range R>
      requires permutable<iterator_t<R>>
      constexpr borrowed_subrange_t<R> rotate(R&& r, iterator_t<R> middle);
  }
  template<class ForwardIter, class OutputIter>
    constexpr OutputIter rotate_copy(ForwardIter first, ForwardIter middle,
                                     ForwardIter last, OutputIter result);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2>
    ForwardIter2 rotate_copy(ExecutionPolicy&& exec, // freestanding-deleted
                             ForwardIter1 first, ForwardIter1 middle,
                             ForwardIter1 last, ForwardIter2 result);
  namespace ranges {
    template<class I, class O>
      using rotate_copy_result = in_out_result<I, O>;
    template<forward_iterator I, sentinel_for<I> S, weakly_incrementable O>
      requires indirectly_copyable<I, O>
      constexpr rotate_copy_result<I, O>
        rotate_copy(I first, I middle, S last, O result);
    template<forward_range R, weakly_incrementable O>
      requires indirectly_copyable<iterator_t<R>, O>
      constexpr rotate_copy_result<borrowed_iterator_t<R>, O>
        rotate_copy(R&& r, iterator_t<R> middle, O result);
  }
  // sample
  template<class PopulationIter, class SampleIter,
           class Distance, class UniformRandomBitGenerator>
    SampleIter sample(PopulationIter first, PopulationIter last,
                      SampleIter out, Distance n, UniformRandomBitGenerator&& g);
  namespace ranges {
    template<input_iterator I, sentinel_for<I> S,
             weakly_incrementable O, class Gen>
      requires (forward_iterator<I> || random_access_iterator<O>) &&
               indirectly_copyable<I, O> &&
               uniform_random_bit_generator<remove_reference_t<Gen>>
      O sample(I first, S last, O out, iter_difference_t<I> n, Gen&& g);
    template<input_range R, weakly_incrementable O, class Gen>
      requires (forward_range<R> || random_access_iterator<O>) &&
               indirectly_copyable<iterator_t<R>, O> &&
               uniform_random_bit_generator<remove_reference_t<Gen>>
      O sample(R&& r, O out, range_difference_t<R> n, Gen&& g);
  }
  // shuffle
  template<class RandomAccessIter, class UniformRandomBitGenerator>
    void shuffle(RandomAccessIter first, RandomAccessIter last,
                 UniformRandomBitGenerator&& g);
  namespace ranges {
    template<random_access_iterator I, sentinel_for<I> S, class Gen>
      requires permutable<I> &&
               uniform_random_bit_generator<remove_reference_t<Gen>>
      I shuffle(I first, S last, Gen&& g);
    template<random_access_range R, class Gen>
      requires permutable<iterator_t<R>> &&
               uniform_random_bit_generator<remove_reference_t<Gen>>
      borrowed_iterator_t<R> shuffle(R&& r, Gen&& g);
  }
  // shift
  template<class ForwardIter>
    constexpr ForwardIter
      shift_left(ForwardIter first, ForwardIter last,
                 typename iterator_traits<ForwardIter>::difference_type n);
  template<class ExecutionPolicy, class ForwardIter>
    ForwardIter
      shift_left(ExecutionPolicy&& exec, // freestanding-deleted
                 ForwardIter first, ForwardIter last,
                 typename iterator_traits<ForwardIter>::difference_type n);
  namespace ranges {
    template<permutable I, sentinel_for<I> S>
      constexpr subrange<I> shift_left(I first, S last, iter_difference_t<I> n);
    template<forward_range R>
      requires permutable<iterator_t<R>>
      constexpr borrowed_subrange_t<R> shift_left(R&& r, range_difference_t<R> n);
  }
  template<class ForwardIter>
    constexpr ForwardIter
      shift_right(ForwardIter first, ForwardIter last,
                  typename iterator_traits<ForwardIter>::difference_type n);
  template<class ExecutionPolicy, class ForwardIter>
    ForwardIter
      shift_right(ExecutionPolicy&& exec, // freestanding-deleted
                  ForwardIter first, ForwardIter last,
                  typename iterator_traits<ForwardIter>::difference_type n);
  namespace ranges {
    template<permutable I, sentinel_for<I> S>
      constexpr subrange<I> shift_right(I first, S last, iter_difference_t<I> n);
    template<forward_range R>
      requires permutable<iterator_t<R>>
      constexpr borrowed_subrange_t<R> shift_right(R&& r, range_difference_t<R> n);
  }
  // sorting and related operations
  // sorting
  template<class RandomAccessIter>
    constexpr void sort(RandomAccessIter first, RandomAccessIter last);
  template<class RandomAccessIter, class Compare>
    constexpr void sort(RandomAccessIter first, RandomAccessIter last, Compare comp);
  template<class ExecutionPolicy, class RandomAccessIter>
    void sort(ExecutionPolicy&& exec, // freestanding-deleted
              RandomAccessIter first, RandomAccessIter last);
  template<class ExecutionPolicy, class RandomAccessIter, class Compare>
    void sort(ExecutionPolicy&& exec, // freestanding-deleted
              RandomAccessIter first, RandomAccessIter last, Compare comp);
  namespace ranges {
    template<random_access_iterator I, sentinel_for<I> S,
             class Comp = ranges::less, class Proj = identity>
      requires sortable<I, Comp, Proj>
      constexpr I sort(I first, S last, Comp comp = {}, Proj proj = {});
    template<random_access_range R, class Comp = ranges::less, class Proj = identity>
      requires sortable<iterator_t<R>, Comp, Proj>
      constexpr borrowed_iterator_t<R> sort(R&& r, Comp comp = {}, Proj proj = {});
  }
  template<class RandomAccessIter>
    void stable_sort(RandomAccessIter first, RandomAccessIter last);               // hosted
  template<class RandomAccessIter, class Compare>
    void stable_sort(RandomAccessIter first, RandomAccessIter last, Compare comp); // hosted
  template<class ExecutionPolicy, class RandomAccessIter>
    void stable_sort(ExecutionPolicy&& exec,                                       // hosted
                     RandomAccessIter first, RandomAccessIter last);
  template<class ExecutionPolicy, class RandomAccessIter, class Compare>
    void stable_sort(ExecutionPolicy&& exec,                                       // hosted
                     RandomAccessIter first, RandomAccessIter last, Compare comp);
  namespace ranges {
    template<random_access_iterator I, sentinel_for<I> S,
             class Comp = ranges::less, class Proj = identity>
      requires sortable<I, Comp, Proj>
      I stable_sort(I first, S last, Comp comp = {}, Proj proj = {});              // hosted
    template<random_access_range R, class Comp = ranges::less, class Proj = identity>
      requires sortable<iterator_t<R>, Comp, Proj>
      borrowed_iterator_t<R> stable_sort(R&& r, Comp comp = {}, Proj proj = {});   // hosted
  }
  template<class RandomAccessIter>
    constexpr void partial_sort(RandomAccessIter first, RandomAccessIter middle,
                                RandomAccessIter last);
  template<class RandomAccessIter, class Compare>
    constexpr void partial_sort(RandomAccessIter first, RandomAccessIter middle,
                                RandomAccessIter last, Compare comp);
  template<class ExecutionPolicy, class RandomAccessIter>
    void partial_sort(ExecutionPolicy&& exec, // freestanding-deleted
                      RandomAccessIter first, RandomAccessIter middle,
                      RandomAccessIter last);
  template<class ExecutionPolicy, class RandomAccessIter, class Compare>
    void partial_sort(ExecutionPolicy&& exec, // freestanding-deleted
                      RandomAccessIter first, RandomAccessIter middle,
                      RandomAccessIter last, Compare comp);
  namespace ranges {
    template<random_access_iterator I, sentinel_for<I> S,
             class Comp = ranges::less, class Proj = identity>
      requires sortable<I, Comp, Proj>
      constexpr I
        partial_sort(I first, I middle, S last, Comp comp = {}, Proj proj = {});
    template<random_access_range R, class Comp = ranges::less, class Proj = identity>
      requires sortable<iterator_t<R>, Comp, Proj>
      constexpr borrowed_iterator_t<R>
        partial_sort(R&& r, iterator_t<R> middle, Comp comp = {}, Proj proj = {});
  }
  template<class InputIter, class RandomAccessIter>
    constexpr RandomAccessIter
      partial_sort_copy(InputIter first, InputIter last,
                        RandomAccessIter result_first,
                        RandomAccessIter result_last);
  template<class InputIter, class RandomAccessIter, class Compare>
    constexpr RandomAccessIter
      partial_sort_copy(InputIter first, InputIter last,
                        RandomAccessIter result_first,
                        RandomAccessIter result_last, Compare comp);
  template<class ExecutionPolicy, class ForwardIter, class RandomAccessIter>
    RandomAccessIter
      partial_sort_copy(ExecutionPolicy&& exec, // freestanding-deleted
                        ForwardIter first, ForwardIter last,
                        RandomAccessIter result_first,
                        RandomAccessIter result_last);
  template<class ExecutionPolicy, class ForwardIter, class RandomAccessIter,
           class Compare>
    RandomAccessIter
      partial_sort_copy(ExecutionPolicy&& exec, // freestanding-deleted
                        ForwardIter first, ForwardIter last,
                        RandomAccessIter result_first,
                        RandomAccessIter result_last, Compare comp);
  namespace ranges {
    template<class I, class O>
      using partial_sort_copy_result = in_out_result<I, O>;
    template<input_iterator I1, sentinel_for<I1> S1,
             random_access_iterator I2, sentinel_for<I2> S2,
             class Comp = ranges::less, class Proj1 = identity, class Proj2 = identity>
      requires indirectly_copyable<I1, I2> && sortable<I2, Comp, Proj2> &&
               indirect_strict_weak_order<Comp, projected<I1, Proj1>,
                                          projected<I2, Proj2>>
      constexpr partial_sort_copy_result<I1, I2>
        partial_sort_copy(I1 first, S1 last, I2 result_first, S2 result_last,
                          Comp comp = {}, Proj1 proj1 = {}, Proj2 proj2 = {});
    template<input_range R1, random_access_range R2, class Comp = ranges::less,
             class Proj1 = identity, class Proj2 = identity>
      requires indirectly_copyable<iterator_t<R1>, iterator_t<R2>> &&
               sortable<iterator_t<R2>, Comp, Proj2> &&
               indirect_strict_weak_order<Comp, projected<iterator_t<R1>, Proj1>,
                                          projected<iterator_t<R2>, Proj2>>
      constexpr partial_sort_copy_result<borrowed_iterator_t<R1>, borrowed_iterator_t<R2>>
        partial_sort_copy(R1&& r, R2&& result_r, Comp comp = {},
                          Proj1 proj1 = {}, Proj2 proj2 = {});
  }
  template<class ForwardIter>
    constexpr bool is_sorted(ForwardIter first, ForwardIter last);
  template<class ForwardIter, class Compare>
    constexpr bool is_sorted(ForwardIter first, ForwardIter last, Compare comp);
  template<class ExecutionPolicy, class ForwardIter>
    bool is_sorted(ExecutionPolicy&& exec, // freestanding-deleted
                   ForwardIter first, ForwardIter last);
  template<class ExecutionPolicy, class ForwardIter, class Compare>
    bool is_sorted(ExecutionPolicy&& exec, // freestanding-deleted
                   ForwardIter first, ForwardIter last, Compare comp);
  namespace ranges {
    template<forward_iterator I, sentinel_for<I> S, class Proj = identity,
             indirect_strict_weak_order<projected<I, Proj>> Comp = ranges::less>
      constexpr bool is_sorted(I first, S last, Comp comp = {}, Proj proj = {});
    template<forward_range R, class Proj = identity,
             indirect_strict_weak_order
                 <projected<iterator_t<R>, Proj>> Comp = ranges::less>
      constexpr bool is_sorted(R&& r, Comp comp = {}, Proj proj = {});
  }
  template<class ForwardIter>
    constexpr ForwardIter is_sorted_until(ForwardIter first, ForwardIter last);
  template<class ForwardIter, class Compare>
    constexpr ForwardIter is_sorted_until(ForwardIter first, ForwardIter last,
                                          Compare comp);
  template<class ExecutionPolicy, class ForwardIter>
    ForwardIter is_sorted_until(ExecutionPolicy&& exec, // freestanding-deleted
                                ForwardIter first, ForwardIter last);
  template<class ExecutionPolicy, class ForwardIter, class Compare>
    ForwardIter is_sorted_until(ExecutionPolicy&& exec, // freestanding-deleted
                                ForwardIter first, ForwardIter last,
                                Compare comp);
  namespace ranges {
    template<forward_iterator I, sentinel_for<I> S, class Proj = identity,
             indirect_strict_weak_order<projected<I, Proj>> Comp = ranges::less>
      constexpr I is_sorted_until(I first, S last, Comp comp = {}, Proj proj = {});
    template<forward_range R, class Proj = identity,
             indirect_strict_weak_order
                 <projected<iterator_t<R>, Proj>> Comp = ranges::less>
      constexpr borrowed_iterator_t<R>
        is_sorted_until(R&& r, Comp comp = {}, Proj proj = {});
  }
  // Nth element
  template<class RandomAccessIter>
    constexpr void nth_element(RandomAccessIter first, RandomAccessIter nth,
                               RandomAccessIter last);
  template<class RandomAccessIter, class Compare>
    constexpr void nth_element(RandomAccessIter first, RandomAccessIter nth,
                               RandomAccessIter last, Compare comp);
  template<class ExecutionPolicy, class RandomAccessIter>
    void nth_element(ExecutionPolicy&& exec, // freestanding-deleted
                     RandomAccessIter first, RandomAccessIter nth,
                     RandomAccessIter last);
  template<class ExecutionPolicy, class RandomAccessIter, class Compare>
    void nth_element(ExecutionPolicy&& exec, // freestanding-deleted
                     RandomAccessIter first, RandomAccessIter nth,
                     RandomAccessIter last, Compare comp);
  namespace ranges {
    template<random_access_iterator I, sentinel_for<I> S,
             class Comp = ranges::less, class Proj = identity>
      requires sortable<I, Comp, Proj>
      constexpr I
        nth_element(I first, I nth, S last, Comp comp = {}, Proj proj = {});
    template<random_access_range R, class Comp = ranges::less, class Proj = identity>
      requires sortable<iterator_t<R>, Comp, Proj>
      constexpr borrowed_iterator_t<R>
        nth_element(R&& r, iterator_t<R> nth, Comp comp = {}, Proj proj = {});
  }
  // binary search
  template<class ForwardIter, class T = typename iterator_traits<ForwardIter>::value_type>
    constexpr ForwardIter lower_bound(ForwardIter first, ForwardIter last,
                                      const T& value);
  template<class ForwardIter, class T = typename iterator_traits<ForwardIter>::value_type,
           class Compare>
    constexpr ForwardIter lower_bound(ForwardIter first, ForwardIter last,
                                      const T& value, Compare comp);
  namespace ranges {
    template<forward_iterator I, sentinel_for<I> S, class Proj = identity,
             class T = projected_value_t<I, Proj>,
             indirect_strict_weak_order<const T*, projected<I, Proj>> Comp = ranges::less>
      constexpr I
          lower_bound(I first, S last, const T& value, Comp comp = {}, Proj proj = {});
    template<forward_range R, class Proj = identity,
             class T = projected_value_t<iterator_t<R>, Proj>,
             indirect_strict_weak_order
                 <const T*, projected<iterator_t<R>, Proj>> Comp = ranges::less>
      constexpr borrowed_iterator_t<R>
        lower_bound(R&& r, const T& value, Comp comp = {}, Proj proj = {});
  }
  template<class ForwardIter, class T = typename iterator_traits<ForwardIter>::value_type>
    constexpr ForwardIter upper_bound(ForwardIter first, ForwardIter last,
                                      const T& value);
  template<class ForwardIter, class T = typename iterator_traits<ForwardIter>::value_type,
           class Compare>
    constexpr ForwardIter upper_bound(ForwardIter first, ForwardIter last,
                                      const T& value, Compare comp);
  namespace ranges {
    template<forward_iterator I, sentinel_for<I> S, class Proj = identity,
             class T = projected_value_t<I, Proj>,
             indirect_strict_weak_order<const T*, projected<I, Proj>> Comp = ranges::less>
      constexpr I
          upper_bound(I first, S last, const T& value, Comp comp = {}, Proj proj = {});
    template<forward_range R, class T, class Proj = identity,
             class T = projected_value_t<iterator_t<R>, Proj>,
             indirect_strict_weak_order
                 <const T*, projected<iterator_t<R>, Proj>> Comp = ranges::less>
      constexpr borrowed_iterator_t<R>
        upper_bound(R&& r, const T& value, Comp comp = {}, Proj proj = {});
  }
  template<class ForwardIter, class T = typename iterator_traits<ForwardIter>::value_type>
    constexpr pair<ForwardIter, ForwardIter>
      equal_range(ForwardIter first, ForwardIter last, const T& value);
  template<class ForwardIter, class T = typename iterator_traits<ForwardIter>::value_type,
           class Compare>
    constexpr pair<ForwardIter, ForwardIter>
      equal_range(ForwardIter first, ForwardIter last, const T& value, Compare comp);
  namespace ranges {
    template<forward_iterator I, sentinel_for<I> S, class Proj = identity,
             class T = projected_value_t<I, Proj>,
             indirect_strict_weak_order<const T*, projected<I, Proj>> Comp = ranges::less>
      constexpr subrange<I>
        equal_range(I first, S last, const T& value, Comp comp = {}, Proj proj = {});
    template<forward_range R, class Proj = identity,
             class T = projected_value_t<iterator_t<R>, Proj>,
             indirect_strict_weak_order
                 <const T*, projected<iterator_t<R>, Proj>> Comp = ranges::less>
      constexpr borrowed_subrange_t<R>
        equal_range(R&& r, const T& value, Comp comp = {}, Proj proj = {});
  }
  template<class ForwardIter, class T = typename iterator_traits<ForwardIter>::value_type>
    constexpr bool binary_search(ForwardIter first, ForwardIter last,
                                 const T& value);
  template<class ForwardIter, class T = typename iterator_traits<ForwardIter>::value_type,
           class Compare>
    constexpr bool binary_search(ForwardIter first, ForwardIter last,
                                 const T& value, Compare comp);
  namespace ranges {
    template<forward_iterator I, sentinel_for<I> S, class Proj = identity,
             class T = projected_value_t<I, Proj>,
             indirect_strict_weak_order<const T*, projected<I, Proj>> Comp = ranges::less>
      constexpr bool binary_search(I first, S last, const T& value,
                                   Comp comp = {}, Proj proj = {});
    template<forward_range R, class Proj = identity,
             class T = projected_value_t<iterator_t<R>, Proj>,
             indirect_strict_weak_order
                 <const T*, projected<iterator_t<R>, Proj>> Comp = ranges::less>
      constexpr bool binary_search(R&& r, const T& value, Comp comp = {}, Proj proj = {});
  }
  // partitions
  template<class InputIter, class Pred>
    constexpr bool is_partitioned(InputIter first, InputIter last, Pred pred);
  template<class ExecutionPolicy, class ForwardIter, class Pred>
    bool is_partitioned(ExecutionPolicy&& exec, // freestanding-deleted
                        ForwardIter first, ForwardIter last, Pred pred);
  namespace ranges {
    template<input_iterator I, sentinel_for<I> S, class Proj = identity,
             indirect_unary_predicate<projected<I, Proj>> Pred>
      constexpr bool is_partitioned(I first, S last, Pred pred, Proj proj = {});
    template<input_range R, class Proj = identity,
             indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
      constexpr bool is_partitioned(R&& r, Pred pred, Proj proj = {});
  }
  template<class ForwardIter, class Pred>
    constexpr ForwardIter partition(ForwardIter first, ForwardIter last, Pred pred);
  template<class ExecutionPolicy, class ForwardIter, class Pred>
    ForwardIter partition(ExecutionPolicy&& exec, // freestanding-deleted
                          ForwardIter first, ForwardIter last, Pred pred);
  namespace ranges {
    template<permutable I, sentinel_for<I> S, class Proj = identity,
             indirect_unary_predicate<projected<I, Proj>> Pred>
      constexpr subrange<I> partition(I first, S last, Pred pred, Proj proj = {});
    template<forward_range R, class Proj = identity,
             indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
      requires permutable<iterator_t<R>>
      constexpr borrowed_subrange_t<R> partition(R&& r, Pred pred, Proj proj = {});
  }
  template<class BidirectionalIter, class Pred>
    BidirectionalIter stable_partition(BidirectionalIter first,                  // hosted
                                       BidirectionalIter last, Pred pred);
  template<class ExecutionPolicy, class BidirectionalIter, class Pred>
    BidirectionalIter stable_partition(ExecutionPolicy&& exec,                   // hosted
                                       BidirectionalIter first,
                                       BidirectionalIter last, Pred pred);
  namespace ranges {
    template<bidirectional_iterator I, sentinel_for<I> S, class Proj = identity,
             indirect_unary_predicate<projected<I, Proj>> Pred>
      requires permutable<I>
      subrange<I> stable_partition(I first, S last, Pred pred, Proj proj = {});  // hosted
    template<bidirectional_range R, class Proj = identity,
             indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
      requires permutable<iterator_t<R>>
      borrowed_subrange_t<R> stable_partition(R&& r, Pred pred, Proj proj = {}); // hosted
  }
  template<class InputIter, class OutputIter1,
           class OutputIter2, class Pred>
    constexpr pair<OutputIter1, OutputIter2>
      partition_copy(InputIter first, InputIter last,
                     OutputIter1 out_true, OutputIter2 out_false, Pred pred);
  template<class ExecutionPolicy, class ForwardIter, class ForwardIter1,
           class ForwardIter2, class Pred>
    pair<ForwardIter1, ForwardIter2>
      partition_copy(ExecutionPolicy&& exec, // freestanding-deleted
                     ForwardIter first, ForwardIter last,
                     ForwardIter1 out_true, ForwardIter2 out_false, Pred pred);
  namespace ranges {
    template<class I, class O1, class O2>
      using partition_copy_result = in_out_out_result<I, O1, O2>;
    template<input_iterator I, sentinel_for<I> S,
             weakly_incrementable O1, weakly_incrementable O2,
             class Proj = identity, indirect_unary_predicate<projected<I, Proj>> Pred>
      requires indirectly_copyable<I, O1> && indirectly_copyable<I, O2>
      constexpr partition_copy_result<I, O1, O2>
        partition_copy(I first, S last, O1 out_true, O2 out_false,
                       Pred pred, Proj proj = {});
    template<input_range R, weakly_incrementable O1, weakly_incrementable O2,
             class Proj = identity,
             indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
      requires indirectly_copyable<iterator_t<R>, O1> &&
               indirectly_copyable<iterator_t<R>, O2>
      constexpr partition_copy_result<borrowed_iterator_t<R>, O1, O2>
        partition_copy(R&& r, O1 out_true, O2 out_false, Pred pred, Proj proj = {});
  }
  template<class ForwardIter, class Pred>
    constexpr ForwardIter
      partition_point(ForwardIter first, ForwardIter last, Pred pred);
  namespace ranges {
    template<forward_iterator I, sentinel_for<I> S, class Proj = identity,
             indirect_unary_predicate<projected<I, Proj>> Pred>
      constexpr I partition_point(I first, S last, Pred pred, Proj proj = {});
    template<forward_range R, class Proj = identity,
             indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
      constexpr borrowed_iterator_t<R>
        partition_point(R&& r, Pred pred, Proj proj = {});
  }
  // merge
  template<class InputIter1, class InputIter2, class OutputIter>
    constexpr OutputIter merge(InputIter1 first1, InputIter1 last1,
                               InputIter2 first2, InputIter2 last2, OutputIter result);
  template<class InputIter1, class InputIter2, class OutputIter,
           class Compare>
    constexpr OutputIter merge(InputIter1 first1, InputIter1 last1,
                               InputIter2 first2, InputIter2 last2,
                               OutputIter result, Compare comp);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class ForwardIter>
    ForwardIter merge(ExecutionPolicy&& exec, // freestanding-deleted
                      ForwardIter1 first1, ForwardIter1 last1,
                      ForwardIter2 first2, ForwardIter2 last2, ForwardIter result);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class ForwardIter, class Compare>
    ForwardIter merge(ExecutionPolicy&& exec, // freestanding-deleted
                      ForwardIter1 first1, ForwardIter1 last1,
                      ForwardIter2 first2, ForwardIter2 last2,
                      ForwardIter result, Compare comp);
  namespace ranges {
    template<class I1, class I2, class O>
      using merge_result = in_in_out_result<I1, I2, O>;
    template<input_iterator I1, sentinel_for<I1> S1, input_iterator I2,
             sentinel_for<I2> S2, weakly_incrementable O, class Comp = ranges::less,
             class Proj1 = identity, class Proj2 = identity>
      requires mergeable<I1, I2, O, Comp, Proj1, Proj2>
      constexpr merge_result<I1, I2, O>
        merge(I1 first1, S1 last1, I2 first2, S2 last2, O result,
              Comp comp = {}, Proj1 proj1 = {}, Proj2 proj2 = {});
    template<input_range R1, input_range R2, weakly_incrementable O,
             class Comp = ranges::less, class Proj1 = identity, class Proj2 = identity>
      requires mergeable<iterator_t<R1>, iterator_t<R2>, O, Comp, Proj1, Proj2>
      constexpr merge_result<borrowed_iterator_t<R1>, borrowed_iterator_t<R2>, O>
        merge(R1&& r1, R2&& r2, O result,
              Comp comp = {}, Proj1 proj1 = {}, Proj2 proj2 = {});
  }
  template<class BidirectionalIter>
    void inplace_merge(BidirectionalIter first, BidirectionalIter middle,         // hosted
                       BidirectionalIter last);
  template<class BidirectionalIter, class Compare>
    void inplace_merge(BidirectionalIter first, BidirectionalIter middle,         // hosted
                       BidirectionalIter last, Compare comp);
  template<class ExecutionPolicy, class BidirectionalIter>
    void inplace_merge(ExecutionPolicy&& exec,                                    // hosted
                       BidirectionalIter first, BidirectionalIter middle,
                       BidirectionalIter last);
  template<class ExecutionPolicy, class BidirectionalIter, class Compare>
    void inplace_merge(ExecutionPolicy&& exec,                                    // hosted
                       BidirectionalIter first, BidirectionalIter middle,
                       BidirectionalIter last, Compare comp);
  namespace ranges {
    template<bidirectional_iterator I, sentinel_for<I> S,
             class Comp = ranges::less, class Proj = identity>
      requires sortable<I, Comp, Proj>
      I inplace_merge(I first, I middle, S last, Comp comp = {}, Proj proj = {}); // hosted
    template<bidirectional_range R, class Comp = ranges::less, class Proj = identity>
      requires sortable<iterator_t<R>, Comp, Proj>
      borrowed_iterator_t<R> inplace_merge(R&& r, iterator_t<R> middle,           // hosted
                                           Comp comp = {}, Proj proj = {});
  }
  // set operations
  template<class InputIter1, class InputIter2>
    constexpr bool includes(InputIter1 first1, InputIter1 last1,
                            InputIter2 first2, InputIter2 last2);
  template<class InputIter1, class InputIter2, class Compare>
    constexpr bool includes(InputIter1 first1, InputIter1 last1,
                            InputIter2 first2, InputIter2 last2, Compare comp);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2>
    bool includes(ExecutionPolicy&& exec, // freestanding-deleted
                  ForwardIter1 first1, ForwardIter1 last1,
                  ForwardIter2 first2, ForwardIter2 last2);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2, class Compare>
    bool includes(ExecutionPolicy&& exec, // freestanding-deleted
                  ForwardIter1 first1, ForwardIter1 last1,
                  ForwardIter2 first2, ForwardIter2 last2, Compare comp);
  namespace ranges {
    template<input_iterator I1, sentinel_for<I1> S1, input_iterator I2,
             sentinel_for<I2> S2, class Proj1 = identity, class Proj2 = identity,
             indirect_strict_weak_order
                 <projected<I1, Proj1>, projected<I2, Proj2>> Comp = ranges::less>
      constexpr bool includes(I1 first1, S1 last1, I2 first2, S2 last2, Comp comp = {},
                              Proj1 proj1 = {}, Proj2 proj2 = {});
    template<input_range R1, input_range R2,
             class Proj1 = identity, class Proj2 = identity,
             indirect_strict_weak_order
                 <projected<iterator_t<R1>, Proj1>,
                  projected<iterator_t<R2>, Proj2>> Comp = ranges::less>
      constexpr bool includes(R1&& r1, R2&& r2, Comp comp = {},
                              Proj1 proj1 = {}, Proj2 proj2 = {});
  }
  template<class InputIter1, class InputIter2, class OutputIter>
    constexpr OutputIter set_union(InputIter1 first1, InputIter1 last1,
                                   InputIter2 first2, InputIter2 last2,
                                   OutputIter result);
  template<class InputIter1, class InputIter2, class OutputIter, class Compare>
    constexpr OutputIter set_union(InputIter1 first1, InputIter1 last1,
                                   InputIter2 first2, InputIter2 last2,
                                   OutputIter result, Compare comp);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class ForwardIter>
    ForwardIter set_union(ExecutionPolicy&& exec, // freestanding-deleted
                          ForwardIter1 first1, ForwardIter1 last1,
                          ForwardIter2 first2, ForwardIter2 last2,
                          ForwardIter result);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class ForwardIter, class Compare>
    ForwardIter set_union(ExecutionPolicy&& exec, // freestanding-deleted
                          ForwardIter1 first1, ForwardIter1 last1,
                          ForwardIter2 first2, ForwardIter2 last2,
                          ForwardIter result, Compare comp);
  namespace ranges {
    template<class I1, class I2, class O>
      using set_union_result = in_in_out_result<I1, I2, O>;
    template<input_iterator I1, sentinel_for<I1> S1, input_iterator I2,
             sentinel_for<I2> S2, weakly_incrementable O, class Comp = ranges::less,
             class Proj1 = identity, class Proj2 = identity>
      requires mergeable<I1, I2, O, Comp, Proj1, Proj2>
      constexpr set_union_result<I1, I2, O>
        set_union(I1 first1, S1 last1, I2 first2, S2 last2, O result, Comp comp = {},
                  Proj1 proj1 = {}, Proj2 proj2 = {});
    template<input_range R1, input_range R2, weakly_incrementable O,
             class Comp = ranges::less, class Proj1 = identity, class Proj2 = identity>
      requires mergeable<iterator_t<R1>, iterator_t<R2>, O, Comp, Proj1, Proj2>
      constexpr set_union_result<borrowed_iterator_t<R1>, borrowed_iterator_t<R2>, O>
        set_union(R1&& r1, R2&& r2, O result, Comp comp = {},
                  Proj1 proj1 = {}, Proj2 proj2 = {});
  }
  template<class InputIter1, class InputIter2, class OutputIter>
    constexpr OutputIter set_intersection(InputIter1 first1, InputIter1 last1,
                                          InputIter2 first2, InputIter2 last2,
                                          OutputIter result);
  template<class InputIter1, class InputIter2, class OutputIter, class Compare>
    constexpr OutputIter set_intersection(InputIter1 first1, InputIter1 last1,
                                          InputIter2 first2, InputIter2 last2,
                                          OutputIter result, Compare comp);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class ForwardIter>
    ForwardIter set_intersection(ExecutionPolicy&& exec, // freestanding-deleted
                                 ForwardIter1 first1, ForwardIter1 last1,
                                 ForwardIter2 first2, ForwardIter2 last2,
                                 ForwardIter result);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class ForwardIter, class Compare>
    ForwardIter set_intersection(ExecutionPolicy&& exec, // freestanding-deleted
                                 ForwardIter1 first1, ForwardIter1 last1,
                                 ForwardIter2 first2, ForwardIter2 last2,
                                 ForwardIter result, Compare comp);
  namespace ranges {
    template<class I1, class I2, class O>
      using set_intersection_result = in_in_out_result<I1, I2, O>;
    template<input_iterator I1, sentinel_for<I1> S1, input_iterator I2,
             sentinel_for<I2> S2, weakly_incrementable O, class Comp = ranges::less,
             class Proj1 = identity, class Proj2 = identity>
      requires mergeable<I1, I2, O, Comp, Proj1, Proj2>
      constexpr set_intersection_result<I1, I2, O>
        set_intersection(I1 first1, S1 last1, I2 first2, S2 last2, O result,
                         Comp comp = {}, Proj1 proj1 = {}, Proj2 proj2 = {});
    template<input_range R1, input_range R2, weakly_incrementable O,
             class Comp = ranges::less, class Proj1 = identity, class Proj2 = identity>
      requires mergeable<iterator_t<R1>, iterator_t<R2>, O, Comp, Proj1, Proj2>
      constexpr set_intersection_result<borrowed_iterator_t<R1>,
                                        borrowed_iterator_t<R2>, O>
        set_intersection(R1&& r1, R2&& r2, O result,
                         Comp comp = {}, Proj1 proj1 = {}, Proj2 proj2 = {});
  }
  template<class InputIter1, class InputIter2, class OutputIter>
    constexpr OutputIter set_difference(InputIter1 first1, InputIter1 last1,
                                        InputIter2 first2, InputIter2 last2,
                                        OutputIter result);
  template<class InputIter1, class InputIter2, class OutputIter, class Compare>
    constexpr OutputIter set_difference(InputIter1 first1, InputIter1 last1,
                                        InputIter2 first2, InputIter2 last2,
                                        OutputIter result, Compare comp);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class ForwardIter>
    ForwardIter set_difference(ExecutionPolicy&& exec, // freestanding-deleted
                               ForwardIter1 first1, ForwardIter1 last1,
                               ForwardIter2 first2, ForwardIter2 last2,
                               ForwardIter result);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class ForwardIter, class Compare>
    ForwardIter set_difference(ExecutionPolicy&& exec, // freestanding-deleted
                               ForwardIter1 first1, ForwardIter1 last1,
                               ForwardIter2 first2, ForwardIter2 last2,
                               ForwardIter result, Compare comp);
  namespace ranges {
    template<class I, class O>
      using set_difference_result = in_out_result<I, O>;
    template<input_iterator I1, sentinel_for<I1> S1, input_iterator I2,
             sentinel_for<I2> S2, weakly_incrementable O, class Comp = ranges::less,
             class Proj1 = identity, class Proj2 = identity>
      requires mergeable<I1, I2, O, Comp, Proj1, Proj2>
      constexpr set_difference_result<I1, O>
        set_difference(I1 first1, S1 last1, I2 first2, S2 last2, O result,
                       Comp comp = {}, Proj1 proj1 = {}, Proj2 proj2 = {});
    template<input_range R1, input_range R2, weakly_incrementable O,
             class Comp = ranges::less, class Proj1 = identity, class Proj2 = identity>
      requires mergeable<iterator_t<R1>, iterator_t<R2>, O, Comp, Proj1, Proj2>
      constexpr set_difference_result<borrowed_iterator_t<R1>, O>
        set_difference(R1&& r1, R2&& r2, O result,
                       Comp comp = {}, Proj1 proj1 = {}, Proj2 proj2 = {});
  }
  template<class InputIter1, class InputIter2, class OutputIter>
    constexpr OutputIter set_symmetric_difference(InputIter1 first1, InputIter1 last1,
                                                  InputIter2 first2, InputIter2 last2,
                                                  OutputIter result);
  template<class InputIter1, class InputIter2, class OutputIter, class Compare>
    constexpr OutputIter set_symmetric_difference(InputIter1 first1, InputIter1 last1,
                                                  InputIter2 first2, InputIter2 last2,
                                                  OutputIter result, Compare comp);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class ForwardIter>
    ForwardIter set_symmetric_difference(ExecutionPolicy&& exec, // freestanding-deleted
                                         ForwardIter1 first1, ForwardIter1 last1,
                                         ForwardIter2 first2, ForwardIter2 last2,
                                         ForwardIter result);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class ForwardIter, class Compare>
    ForwardIter set_symmetric_difference(ExecutionPolicy&& exec, // freestanding-deleted
                                         ForwardIter1 first1, ForwardIter1 last1,
                                         ForwardIter2 first2, ForwardIter2 last2,
                                         ForwardIter result, Compare comp);
  namespace ranges {
    template<class I1, class I2, class O>
      using set_symmetric_difference_result = in_in_out_result<I1, I2, O>;
    template<input_iterator I1, sentinel_for<I1> S1, input_iterator I2,
             sentinel_for<I2> S2, weakly_incrementable O, class Comp = ranges::less,
             class Proj1 = identity, class Proj2 = identity>
      requires mergeable<I1, I2, O, Comp, Proj1, Proj2>
      constexpr set_symmetric_difference_result<I1, I2, O>
        set_symmetric_difference(I1 first1, S1 last1, I2 first2, S2 last2, O result,
                                 Comp comp = {}, Proj1 proj1 = {}, Proj2 proj2 = {});
    template<input_range R1, input_range R2, weakly_incrementable O,
             class Comp = ranges::less, class Proj1 = identity, class Proj2 = identity>
      requires mergeable<iterator_t<R1>, iterator_t<R2>, O, Comp, Proj1, Proj2>
      constexpr set_symmetric_difference_result<borrowed_iterator_t<R1>,
                                                borrowed_iterator_t<R2>, O>
        set_symmetric_difference(R1&& r1, R2&& r2, O result, Comp comp = {},
                                 Proj1 proj1 = {}, Proj2 proj2 = {});
  }
  // heap operations
  template<class RandomAccessIter>
    constexpr void push_heap(RandomAccessIter first, RandomAccessIter last);
  template<class RandomAccessIter, class Compare>
    constexpr void push_heap(RandomAccessIter first, RandomAccessIter last,
                             Compare comp);
  namespace ranges {
    template<random_access_iterator I, sentinel_for<I> S,
             class Comp = ranges::less, class Proj = identity>
      requires sortable<I, Comp, Proj>
      constexpr I push_heap(I first, S last, Comp comp = {}, Proj proj = {});
    template<random_access_range R, class Comp = ranges::less, class Proj = identity>
      requires sortable<iterator_t<R>, Comp, Proj>
      constexpr borrowed_iterator_t<R> push_heap(R&& r, Comp comp = {}, Proj proj = {});
  }
  template<class RandomAccessIter>
    constexpr void pop_heap(RandomAccessIter first, RandomAccessIter last);
  template<class RandomAccessIter, class Compare>
    constexpr void pop_heap(RandomAccessIter first, RandomAccessIter last,
                            Compare comp);
  namespace ranges {
    template<random_access_iterator I, sentinel_for<I> S,
             class Comp = ranges::less, class Proj = identity>
      requires sortable<I, Comp, Proj>
      constexpr I pop_heap(I first, S last, Comp comp = {}, Proj proj = {});
    template<random_access_range R, class Comp = ranges::less, class Proj = identity>
      requires sortable<iterator_t<R>, Comp, Proj>
      constexpr borrowed_iterator_t<R> pop_heap(R&& r, Comp comp = {}, Proj proj = {});
  }
  template<class RandomAccessIter>
    constexpr void make_heap(RandomAccessIter first, RandomAccessIter last);
  template<class RandomAccessIter, class Compare>
    constexpr void make_heap(RandomAccessIter first, RandomAccessIter last,
                             Compare comp);
  namespace ranges {
    template<random_access_iterator I, sentinel_for<I> S,
             class Comp = ranges::less, class Proj = identity>
      requires sortable<I, Comp, Proj>
      constexpr I make_heap(I first, S last, Comp comp = {}, Proj proj = {});
    template<random_access_range R, class Comp = ranges::less, class Proj = identity>
      requires sortable<iterator_t<R>, Comp, Proj>
      constexpr borrowed_iterator_t<R> make_heap(R&& r, Comp comp = {}, Proj proj = {});
  }
  template<class RandomAccessIter>
    constexpr void sort_heap(RandomAccessIter first, RandomAccessIter last);
  template<class RandomAccessIter, class Compare>
    constexpr void sort_heap(RandomAccessIter first, RandomAccessIter last,
                             Compare comp);
  namespace ranges {
    template<random_access_iterator I, sentinel_for<I> S,
             class Comp = ranges::less, class Proj = identity>
      requires sortable<I, Comp, Proj>
      constexpr I sort_heap(I first, S last, Comp comp = {}, Proj proj = {});
    template<random_access_range R, class Comp = ranges::less, class Proj = identity>
      requires sortable<iterator_t<R>, Comp, Proj>
      constexpr borrowed_iterator_t<R> sort_heap(R&& r, Comp comp = {}, Proj proj = {});
  }
  template<class RandomAccessIter>
    constexpr bool is_heap(RandomAccessIter first, RandomAccessIter last);
  template<class RandomAccessIter, class Compare>
    constexpr bool is_heap(RandomAccessIter first, RandomAccessIter last,
                           Compare comp);
  template<class ExecutionPolicy, class RandomAccessIter>
    bool is_heap(ExecutionPolicy&& exec, // freestanding-deleted
                 RandomAccessIter first, RandomAccessIter last);
  template<class ExecutionPolicy, class RandomAccessIter, class Compare>
    bool is_heap(ExecutionPolicy&& exec, // freestanding-deleted
                 RandomAccessIter first, RandomAccessIter last, Compare comp);
  namespace ranges {
    template<random_access_iterator I, sentinel_for<I> S, class Proj = identity,
             indirect_strict_weak_order<projected<I, Proj>> Comp = ranges::less>
      constexpr bool is_heap(I first, S last, Comp comp = {}, Proj proj = {});
    template<random_access_range R, class Proj = identity,
             indirect_strict_weak_order
                 <projected<iterator_t<R>, Proj>> Comp = ranges::less>
      constexpr bool is_heap(R&& r, Comp comp = {}, Proj proj = {});
  }
  template<class RandomAccessIter>
    constexpr RandomAccessIter
      is_heap_until(RandomAccessIter first, RandomAccessIter last);
  template<class RandomAccessIter, class Compare>
    constexpr RandomAccessIter
      is_heap_until(RandomAccessIter first, RandomAccessIter last, Compare comp);
  template<class ExecutionPolicy, class RandomAccessIter>
    RandomAccessIter
      is_heap_until(ExecutionPolicy&& exec, // freestanding-deleted
                    RandomAccessIter first, RandomAccessIter last);
  template<class ExecutionPolicy, class RandomAccessIter, class Compare>
    RandomAccessIter
      is_heap_until(ExecutionPolicy&& exec, // freestanding-deleted
                    RandomAccessIter first, RandomAccessIter last, Compare comp);
  namespace ranges {
    template<random_access_iterator I, sentinel_for<I> S, class Proj = identity,
             indirect_strict_weak_order<projected<I, Proj>> Comp = ranges::less>
      constexpr I is_heap_until(I first, S last, Comp comp = {}, Proj proj = {});
    template<random_access_range R, class Proj = identity,
             indirect_strict_weak_order
                 <projected<iterator_t<R>, Proj>> Comp = ranges::less>
      constexpr borrowed_iterator_t<R>
        is_heap_until(R&& r, Comp comp = {}, Proj proj = {});
  }
  // minimum and maximum
  template<class T> constexpr const T& min(const T& a, const T& b);
  template<class T, class Compare>
    constexpr const T& min(const T& a, const T& b, Compare comp);
  template<class T>
    constexpr T min(initializer_list<T> t);
  template<class T, class Compare>
    constexpr T min(initializer_list<T> t, Compare comp);
  namespace ranges {
    template<class T, class Proj = identity,
             indirect_strict_weak_order<projected<const T*, Proj>> Comp = ranges::less>
      constexpr const T& min(const T& a, const T& b, Comp comp = {}, Proj proj = {});
    template<copyable T, class Proj = identity,
             indirect_strict_weak_order<projected<const T*, Proj>> Comp = ranges::less>
      constexpr T min(initializer_list<T> r, Comp comp = {}, Proj proj = {});
    template<input_range R, class Proj = identity,
             indirect_strict_weak_order
                 <projected<iterator_t<R>, Proj>> Comp = ranges::less>
      requires indirectly_copyable_storable<iterator_t<R>, range_value_t<R>*>
      constexpr range_value_t<R> min(R&& r, Comp comp = {}, Proj proj = {});
  }
  template<class T> constexpr const T& max(const T& a, const T& b);
  template<class T, class Compare>
    constexpr const T& max(const T& a, const T& b, Compare comp);
  template<class T>
    constexpr T max(initializer_list<T> t);
  template<class T, class Compare>
    constexpr T max(initializer_list<T> t, Compare comp);
  namespace ranges {
    template<class T, class Proj = identity,
             indirect_strict_weak_order<projected<const T*, Proj>> Comp = ranges::less>
      constexpr const T& max(const T& a, const T& b, Comp comp = {}, Proj proj = {});
    template<copyable T, class Proj = identity,
             indirect_strict_weak_order<projected<const T*, Proj>> Comp = ranges::less>
      constexpr T max(initializer_list<T> r, Comp comp = {}, Proj proj = {});
    template<input_range R, class Proj = identity,
             indirect_strict_weak_order
                 <projected<iterator_t<R>, Proj>> Comp = ranges::less>
      requires indirectly_copyable_storable<iterator_t<R>, range_value_t<R>*>
      constexpr range_value_t<R> max(R&& r, Comp comp = {}, Proj proj = {});
  }
  template<class T> constexpr pair<const T&, const T&> minmax(const T& a, const T& b);
  template<class T, class Compare>
    constexpr pair<const T&, const T&> minmax(const T& a, const T& b, Compare comp);
  template<class T>
    constexpr pair<T, T> minmax(initializer_list<T> t);
  template<class T, class Compare>
    constexpr pair<T, T> minmax(initializer_list<T> t, Compare comp);
  namespace ranges {
    template<class T>
      using minmax_result = min_max_result<T>;
    template<class T, class Proj = identity,
             indirect_strict_weak_order<projected<const T*, Proj>> Comp = ranges::less>
      constexpr minmax_result<const T&>
        minmax(const T& a, const T& b, Comp comp = {}, Proj proj = {});
    template<copyable T, class Proj = identity,
             indirect_strict_weak_order<projected<const T*, Proj>> Comp = ranges::less>
      constexpr minmax_result<T>
        minmax(initializer_list<T> r, Comp comp = {}, Proj proj = {});
    template<input_range R, class Proj = identity,
             indirect_strict_weak_order
                 <projected<iterator_t<R>, Proj>> Comp = ranges::less>
      requires indirectly_copyable_storable<iterator_t<R>, range_value_t<R>*>
      constexpr minmax_result<range_value_t<R>>
        minmax(R&& r, Comp comp = {}, Proj proj = {});
  }
  template<class ForwardIter>
    constexpr ForwardIter min_element(ForwardIter first, ForwardIter last);
  template<class ForwardIter, class Compare>
    constexpr ForwardIter min_element(ForwardIter first, ForwardIter last,
                                      Compare comp);
  template<class ExecutionPolicy, class ForwardIter>
    ForwardIter min_element(ExecutionPolicy&& exec, // freestanding-deleted
                            ForwardIter first, ForwardIter last);
  template<class ExecutionPolicy, class ForwardIter, class Compare>
    ForwardIter min_element(ExecutionPolicy&& exec, // freestanding-deleted
                            ForwardIter first, ForwardIter last,
                            Compare comp);
  namespace ranges {
    template<forward_iterator I, sentinel_for<I> S, class Proj = identity,
             indirect_strict_weak_order<projected<I, Proj>> Comp = ranges::less>
      constexpr I min_element(I first, S last, Comp comp = {}, Proj proj = {});
    template<forward_range R, class Proj = identity,
             indirect_strict_weak_order
                 <projected<iterator_t<R>, Proj>> Comp = ranges::less>
      constexpr borrowed_iterator_t<R>
        min_element(R&& r, Comp comp = {}, Proj proj = {});
  }
  template<class ForwardIter>
    constexpr ForwardIter max_element(ForwardIter first, ForwardIter last);
  template<class ForwardIter, class Compare>
    constexpr ForwardIter max_element(ForwardIter first, ForwardIter last,
                                      Compare comp);
  template<class ExecutionPolicy, class ForwardIter>
    ForwardIter max_element(ExecutionPolicy&& exec, // freestanding-deleted
                            ForwardIter first, ForwardIter last);
  template<class ExecutionPolicy, class ForwardIter, class Compare>
    ForwardIter max_element(ExecutionPolicy&& exec, // freestanding-deleted
                            ForwardIter first, ForwardIter last,
                            Compare comp);
  namespace ranges {
    template<forward_iterator I, sentinel_for<I> S, class Proj = identity,
             indirect_strict_weak_order<projected<I, Proj>> Comp = ranges::less>
      constexpr I max_element(I first, S last, Comp comp = {}, Proj proj = {});
    template<forward_range R, class Proj = identity,
             indirect_strict_weak_order
                 <projected<iterator_t<R>, Proj>> Comp = ranges::less>
      constexpr borrowed_iterator_t<R>
        max_element(R&& r, Comp comp = {}, Proj proj = {});
  }
  template<class ForwardIter>
    constexpr pair<ForwardIter, ForwardIter>
      minmax_element(ForwardIter first, ForwardIter last);
  template<class ForwardIter, class Compare>
    constexpr pair<ForwardIter, ForwardIter>
      minmax_element(ForwardIter first, ForwardIter last, Compare comp);
  template<class ExecutionPolicy, class ForwardIter>
    pair<ForwardIter, ForwardIter>
      minmax_element(ExecutionPolicy&& exec, // freestanding-deleted
                     ForwardIter first, ForwardIter last);
  template<class ExecutionPolicy, class ForwardIter, class Compare>
    pair<ForwardIter, ForwardIter>
      minmax_element(ExecutionPolicy&& exec, // freestanding-deleted
                     ForwardIter first, ForwardIter last, Compare comp);
  namespace ranges {
    template<class I>
      using minmax_element_result = min_max_result<I>;
    template<forward_iterator I, sentinel_for<I> S, class Proj = identity,
             indirect_strict_weak_order<projected<I, Proj>> Comp = ranges::less>
      constexpr minmax_element_result<I>
        minmax_element(I first, S last, Comp comp = {}, Proj proj = {});
    template<forward_range R, class Proj = identity,
             indirect_strict_weak_order
                 <projected<iterator_t<R>, Proj>> Comp = ranges::less>
      constexpr minmax_element_result<borrowed_iterator_t<R>>
        minmax_element(R&& r, Comp comp = {}, Proj proj = {});
  }
  // bounded value
  template<class T>
    constexpr const T& clamp(const T& v, const T& lo, const T& hi);
  template<class T, class Compare>
    constexpr const T& clamp(const T& v, const T& lo, const T& hi, Compare comp);
  namespace ranges {
    template<class T, class Proj = identity,
             indirect_strict_weak_order<projected<const T*, Proj>> Comp = ranges::less>
      constexpr const T&
        clamp(const T& v, const T& lo, const T& hi, Comp comp = {}, Proj proj = {});
  }
  // lexicographical comparison
  template<class InputIter1, class InputIter2>
    constexpr bool lexicographical_compare(InputIter1 first1, InputIter1 last1,
                                           InputIter2 first2, InputIter2 last2);
  template<class InputIter1, class InputIter2, class Compare>
    constexpr bool lexicographical_compare(InputIter1 first1, InputIter1 last1,
                                           InputIter2 first2, InputIter2 last2,
                                           Compare comp);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2>
    bool lexicographical_compare(ExecutionPolicy&& exec, // freestanding-deleted
                                 ForwardIter1 first1, ForwardIter1 last1,
                                 ForwardIter2 first2, ForwardIter2 last2);
  template<class ExecutionPolicy, class ForwardIter1, class ForwardIter2,
           class Compare>
    bool lexicographical_compare(ExecutionPolicy&& exec, // freestanding-deleted
                                 ForwardIter1 first1, ForwardIter1 last1,
                                 ForwardIter2 first2, ForwardIter2 last2,
                                 Compare comp);
  namespace ranges {
    template<input_iterator I1, sentinel_for<I1> S1, input_iterator I2,
             sentinel_for<I2> S2, class Proj1 = identity, class Proj2 = identity,
             indirect_strict_weak_order
                 <projected<I1, Proj1>, projected<I2, Proj2>> Comp = ranges::less>
      constexpr bool
        lexicographical_compare(I1 first1, S1 last1, I2 first2, S2 last2,
                                Comp comp = {}, Proj1 proj1 = {}, Proj2 proj2 = {});
    template<input_range R1, input_range R2, class Proj1 = identity,
             class Proj2 = identity,
             indirect_strict_weak_order
                 <projected<iterator_t<R1>, Proj1>,
                            projected<iterator_t<R2>, Proj2>> Comp = ranges::less>
      constexpr bool
        lexicographical_compare(R1&& r1, R2&& r2, Comp comp = {},
                                Proj1 proj1 = {}, Proj2 proj2 = {});
  }
  // three-way comparison algorithms
  template<class InputIter1, class InputIter2, class Cmp>
    constexpr auto lexicographical_compare_three_way(InputIter1 b1, InputIter1 e1,
                                                     InputIter2 b2, InputIter2 e2,
                                                     Cmp comp)
        -> decltype(comp(*b1, *b2));
  template<class InputIter1, class InputIter2>
    constexpr auto lexicographical_compare_three_way(InputIter1 b1, InputIter1 e1,
                                                     InputIter2 b2, InputIter2 e2);
  // permutations
  template<class BidirectionalIter>
    constexpr bool next_permutation(BidirectionalIter first,
                                    BidirectionalIter last);
  template<class BidirectionalIter, class Compare>
    constexpr bool next_permutation(BidirectionalIter first,
                                    BidirectionalIter last, Compare comp);
  namespace ranges {
    template<class I>
      using next_permutation_result = in_found_result<I>;
    template<bidirectional_iterator I, sentinel_for<I> S, class Comp = ranges::less,
             class Proj = identity>
      requires sortable<I, Comp, Proj>
      constexpr next_permutation_result<I>
        next_permutation(I first, S last, Comp comp = {}, Proj proj = {});
    template<bidirectional_range R, class Comp = ranges::less, class Proj = identity>
      requires sortable<iterator_t<R>, Comp, Proj>
      constexpr next_permutation_result<borrowed_iterator_t<R>>
        next_permutation(R&& r, Comp comp = {}, Proj proj = {});
  }
  template<class BidirectionalIter>
    constexpr bool prev_permutation(BidirectionalIter first,
                                    BidirectionalIter last);
  template<class BidirectionalIter, class Compare>
    constexpr bool prev_permutation(BidirectionalIter first,
                                    BidirectionalIter last, Compare comp);
  namespace ranges {
    template<class I>
      using prev_permutation_result = in_found_result<I>;
    template<bidirectional_iterator I, sentinel_for<I> S, class Comp = ranges::less,
             class Proj = identity>
      requires sortable<I, Comp, Proj>
      constexpr prev_permutation_result<I>
        prev_permutation(I first, S last, Comp comp = {}, Proj proj = {});
    template<bidirectional_range R, class Comp = ranges::less, class Proj = identity>
      requires sortable<iterator_t<R>, Comp, Proj>
      constexpr prev_permutation_result<borrowed_iterator_t<R>>
        prev_permutation(R&& r, Comp comp = {}, Proj proj = {});
  }
}

    类模板 ranges::in_fun_result

    namespace std::ranges {
  template<class I, class F>
  struct in_fun_result {
    [[no_unique_address]] I in;
    [[no_unique_address]] F fun;

    template<class I2, class F2>
      requires convertible_to<const I&, I2> && convertible_to<const F&, F2>
    constexpr operator in_fun_result<I2, F2>() const & {
      return {in, fun};
    }

    template<class I2, class F2>
      requires convertible_to<I, I2> && convertible_to<F, F2>
    constexpr operator in_fun_result<I2, F2>() && {
      return {std::move(in), std::move(fun)};
    }
  };
}

    类模板 ranges::in_in_result

    namespace std::ranges {
  template<class I1, class I2>
  struct in_in_result {
    [[no_unique_address]] I1 in1;
    [[no_unique_address]] I2 in2;

    template<class II1, class II2>
      requires convertible_to<const I1&, II1> && convertible_to<const I2&, II2>
    constexpr operator in_in_result<II1, II2>() const & {
      return {in1, in2};
    }

    template<class II1, class II2>
      requires convertible_to<I1, II1> && convertible_to<I2, II2>
    constexpr operator in_in_result<II1, II2>() && {
      return {std::move(in1), std::move(in2)};
    }
  };
}

    类模板 ranges::in_out_result

    namespace std::ranges {
  template<class I, class O>
  struct in_out_result {
    [[no_unique_address]] I in;
    [[no_unique_address]] O out;

    template<class I2, class O2>
      requires convertible_to<const I&, I2> && convertible_to<const O&, O2>
    constexpr operator in_out_result<I2, O2>() const & {
      return {in, out};
    }

    template<class I2, class O2>
      requires convertible_to<I, I2> && convertible_to<O, O2>
    constexpr operator in_out_result<I2, O2>() && {
      return {std::move(in), std::move(out)};
    }
  };
}

    类模板 ranges::in_in_out_result

    namespace std::ranges {
  template<class I1, class I2, class O>
  struct in_in_out_result {
    [[no_unique_address]] I1 in1;
    [[no_unique_address]] I2 in2;
    [[no_unique_address]] O  out;

    template<class II1, class II2, class OO>
      requires convertible_to<const I1&, II1> &&
               convertible_to<const I2&, II2> &&
               convertible_to<const O&, OO>
    constexpr operator in_in_out_result<II1, II2, OO>() const & {
      return {in1, in2, out};
    }

    template<class II1, class II2, class OO>
      requires convertible_to<I1, II1> &&
               convertible_to<I2, II2> &&
               convertible_to<O, OO>
    constexpr operator in_in_out_result<II1, II2, OO>() && {
      return {std::move(in1), std::move(in2), std::move(out)};
    }
  };
}

    类模板 ranges::in_out_out_result

    namespace std::ranges {
  template<class I, class O1, class O2>
  struct in_out_out_result {
    [[no_unique_address]] I  in;
    [[no_unique_address]] O1 out1;
    [[no_unique_address]] O2 out2;

    template<class II, class OO1, class OO2>
      requires convertible_to<const I&, II> &&
               convertible_to<const O1&, OO1> &&
               convertible_to<const O2&, OO2>
    constexpr operator in_out_out_result<II, OO1, OO2>() const & {
      return {in, out1, out2};
    }

    template<class II, class OO1, class OO2>
      requires convertible_to<I, II> &&
               convertible_to<O1, OO1> &&
               convertible_to<O2, OO2>
    constexpr operator in_out_out_result<II, OO1, OO2>() && {
      return {std::move(in), std::move(out1), std::move(out2)};
    }
  };
}

    类模板 ranges::min_max_result

    namespace std::ranges {
  template<class T>
  struct min_max_result {
    [[no_unique_address]] T min;
    [[no_unique_address]] T max;

    template<class T2>
      requires convertible_to<const T&, T2>
    constexpr operator min_max_result<T2>() const & {
      return {min, max};
    }

    template<class T2>
      requires convertible_to<T, T2>
    constexpr operator min_max_result<T2>() && {
      return {std::move(min), std::move(max)};
    }
  };
}

    类模板 ranges::in_found_result

    namespace std::ranges {
  template<class I>
  struct in_found_result {
    [[no_unique_address]] I in;
    bool found;

    template<class I2>
      requires convertible_to<const I&, I2>
    constexpr operator in_found_result<I2>() const & {
      return {in, found};
    }
    template<class I2>
      requires convertible_to<I, I2>
    constexpr operator in_found_result<I2>() && {
      return {std::move(in), found};
    }
  };
}

    类模板 ranges::in_value_result

    namespace std::ranges {
template<class I, class T>
  struct in_value_result {
    [[no_unique_address]] I in;
    [[no_unique_address]] T value;
 
    template<class I2, class T2>
      requires convertible_to<const I&, I2> && convertible_to<const T&, T2>
    constexpr operator in_value_result<I2, T2>() const & {
      return {in, value};
    }
 
    template<class I2, class T2>
      requires convertible_to<I, I2> && convertible_to<T, T2>
    constexpr operator in_value_result<I2, T2>() && {
      return {std::move(in), std::move(value)};
    }
  };
}

    类模板 ranges::out_value_result

    namespace std::ranges {
template<class O, class T>
  struct out_value_result {
    [[no_unique_address]] O out;
    [[no_unique_address]] T value;

    template<class O2, class T2>
      requires convertible_to<const O&, O2> && convertible_to<const T&, T2>
    constexpr operator out_value_result<O2, T2>() const & {
      return {out, value};
    }

    template<class O2, class T2>
      requires convertible_to<O, O2> && convertible_to<T, T2>
    constexpr operator out_value_result<O2, T2>() && {
      return {std::move(out), std::move(value)};
    }
  };
}