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std::ranges::sort_heap - cppreference.com

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Defined in header <algorithm>

Call signature

template< std::random_access_iterator I, std::sentinel_for<I> S, class Comp = ranges::less, class Proj = std::identity > requires std::sortable<I, Comp, Proj> constexpr I sort_heap( I first, S last, Comp comp = {}, Proj proj = {} );

 (1) (since C++20)

template< ranges::random_access_range R, class Comp = ranges::less, class Proj = std::identity > requires std::sortable<ranges::iterator_t<R>, Comp, Proj> constexpr ranges::borrowed_iterator_t<R> sort_heap( R&& r, Comp comp = {}, Proj proj = {} );

 (2) (since C++20)

Sorts the elements in the specified range with respect to comp and proj, where the range originally represents a heap with respect to comp and proj. The sorted range no longer maintains the heap property.

1) The specified range is [first, last).

2) The specified range is r.

If the specified range is not a heap with respect to comp and proj, the behavior is undefined.

The function-like entities described on this page are algorithm function objects (informally known as niebloids), that is:

Parameters

first, last - the iterator-sentinel pair defining the range of elements to modify
r - the range of elements to modify
comp - comparator to apply to the projected elements
proj - projection to apply to the elements

Return value

1) last

2) ranges::end(r)

Complexity

At most 2N⋅log(N) applications of comp and 4N⋅log(N) applications of proj, where N is:

1) ranges::distance(first, last)

2) ranges::distance(r)

Possible implementation

struct sort_heap_fn
{
    template<std::random_access_iterator I, std::sentinel_for<I> S,
             class Comp = ranges::less, class Proj = std::identity>
        requires std::sortable<I, Comp, Proj>
    constexpr I operator()(I first, S last, Comp comp = {}, Proj proj = {}) const
    {
        auto ret{ranges::next(first, last)};
        for (auto last{ret}; first != last; --last)
            ranges::pop_heap(first, last, comp, proj);
        return ret;
    }

    template<ranges::random_access_range R,
             class Comp = ranges::less, class Proj = std::identity>
        requires std::sortable<ranges::iterator_t<R>, Comp, Proj>
    constexpr ranges::borrowed_iterator_t<R>
        operator()(R&& r, Comp comp = {}, Proj proj = {}) const
    {
        return (*this)(ranges::begin(r), ranges::end(r), std::move(comp), std::move(proj));
    }
};

inline constexpr sort_heap_fn sort_heap{};

Example

#include <algorithm>
#include <array>
#include <iostream>

void print(auto const& rem, const auto& v)
{
    std::cout << rem;
    for (const auto i : v)
        std::cout << i << ' ';
    std::cout << '\n';
}

int main()
{
    std::array v{3, 1, 4, 1, 5, 9};
    print("original array:  ", v);
    
    std::ranges::make_heap(v);
    print("after make_heap: ", v);
    
    std::ranges::sort_heap(v);
    print("after sort_heap: ", v);
}

Output: 

original array:  3 1 4 1 5 9
after make_heap: 9 5 4 1 1 3
after sort_heap: 1 1 3 4 5 9

See also

checks if the given range is a max heap
(algorithm function object)[edit]
finds the largest subrange that is a max heap
(algorithm function object)[edit]
creates a max heap out of a range of elements
(algorithm function object)[edit]
removes the largest element from a max heap
(algorithm function object)[edit]
adds an element to a max heap
(algorithm function object)[edit]
turns a max heap into a range of elements sorted in ascending order
(function template) [edit]