std::ranges:: pop_heap

Swaps the first element and the last element of the specified heap with respect to comp and proj and makes the subrange excluding the first position into a heap with respect to comp and proj . This has the effect of removing the first element from the specified heap.

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

• Explicit template argument lists cannot be specified when calling any of them.
• None of them are visible to argument-dependent lookup .
• When any of them are found by normal unqualified lookup as the name to the left of the function-call operator, argument-dependent lookup is inhibited.

Parameters

Return value

Complexity

At most \(\scriptsize 2\log{(N)}\) 2log(N) applications of comp and \(\scriptsize 4\log{(N)}\) 4log(N) applications of proj , where \(\scriptsize N \) N is:

Example

#include <algorithm>
#include <array>
#include <iostream>
#include <iterator>
#include <string_view>
 
template<class I = int*>
void print(std::string_view rem, I first = {}, I last = {},
           std::string_view term = "\n")
{
    for (std::cout << rem; first != last; ++first)
        std::cout << *first << ' ';
    std::cout << term;
}
 
int main()
{
    std::array v{3, 1, 4, 1, 5, 9, 2, 6, 5, 3};
    print("initially, v: ", v.cbegin(), v.cend());
 
    std::ranges::make_heap(v);
    print("make_heap, v: ", v.cbegin(), v.cend());
 
    print("convert heap into sorted array:");
    for (auto n {std::ssize(v)}; n >= 0; --n)
    {
        std::ranges::pop_heap(v.begin(), v.begin() + n);
        print("[ ", v.cbegin(), v.cbegin() + n, "]  ");
        print("[ ", v.cbegin() + n, v.cend(), "]\n");
    }
}

initially, v: 3 1 4 1 5 9 2 6 5 3
make_heap, v: 9 6 4 5 5 3 2 1 1 3
convert heap into sorted array:
[ 6 5 4 3 5 3 2 1 1 9 ]  [ ]
[ 5 5 4 3 1 3 2 1 6 ]  [ 9 ]
[ 5 3 4 1 1 3 2 5 ]  [ 6 9 ]
[ 4 3 3 1 1 2 5 ]  [ 5 6 9 ]
[ 3 2 3 1 1 4 ]  [ 5 5 6 9 ]
[ 3 2 1 1 3 ]  [ 4 5 5 6 9 ]
[ 2 1 1 3 ]  [ 3 4 5 5 6 9 ]
[ 1 1 2 ]  [ 3 3 4 5 5 6 9 ]
[ 1 1 ]  [ 2 3 3 4 5 5 6 9 ]
[ 1 ]  [ 1 2 3 3 4 5 5 6 9 ]
[ ]  [ 1 1 2 3 3 4 5 5 6 9 ]

See also