std::ranges::pop_heap
From cppreference.com
| Defined in header <algorithm>
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| Call signature |
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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 pop_heap( I first, S last, Comp comp = {}, Proj proj = {} );
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(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>
pop_heap( R&& r, Comp comp = {}, Proj proj = {} );
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(2) | (since C++20) |
Removes the first element from the non-empty heap with respect to comp and proj represented by the target range [first, last) or r by swapping its first value and last value. The heap after the removal will not include the last element of the target range.
If the target range is not a valid non-empty 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:
- 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
| first, last | - | the iterator-sentinel pair defining the target range |
| r | - | the target range |
| comp | - | the comparator to be applied to the (projected) elements |
| proj | - | the projection to be applied to the elements |
Return value
The past-the-end iterator of the target range.
Complexity
Given N as ranges::distance(first, last) or ranges::distance(r):
1,2) At most 2log(N) applications of
comp, and twice as many applications of proj.Example
Run this code
#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");
}
}
Output:
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
| removes the largest element from a max heap (function template) | |
(C++20) |
adds an element to a max heap (algorithm function object) |
(C++20) |
checks if the given range is a max heap (algorithm function object) |
(C++20) |
finds the largest subrange that is a max heap (algorithm function object) |
(C++20) |
creates a max heap out of a range of elements (algorithm function object) |
(C++20) |
turns a max heap into a sorted range of elements (algorithm function object) |