Defined in header <algorithm>  

(1)  
template< class RandomIt > void pop_heap( RandomIt first, RandomIt last );  (until C++20)  
template< class RandomIt > constexpr void pop_heap( RandomIt first, RandomIt last );  (since C++20)  
(2)  
template< class RandomIt, class Compare > void pop_heap( RandomIt first, RandomIt last, Compare comp );  (until C++20)  
template< class RandomIt, class Compare > constexpr void pop_heap( RandomIt first, RandomIt last, Compare comp );  (since C++20) 
Swaps the value in the position first
and the value in the position last1
and makes the subrange [first, last1)
into a heap. This has the effect of removing the first element from the heap defined by the range [first, last)
.
The first version of the function uses operator<
to compare the elements, which makes the heap a max heap. The second uses the given comparison function comp
.
first, last    the range of elements defining the valid nonempty heap to modify 
comp    comparison function object (i.e. an object that satisfies the requirements of Compare) which returns true if the first argument is less than the second. The signature of the comparison function should be equivalent to the following:
While the signature does not need to have 
Type requirements  
RandomIt must meet the requirements of ValueSwappable and LegacyRandomAccessIterator. 

The type of dereferenced RandomIt must meet the requirements of MoveAssignable and MoveConstructible. 
(none).
At most 2×log(N) comparisons where N=std::distance(first, last)
.
A max heap is a range of elements [f,l)
that has the following properties:
N = lf
, for all 0 < i < N
, f[(i1)/2]
does not compare less than f[i]
. std::push_heap
, in \(\scriptsize \mathcal{O}(\log N)\)𝓞(log N) time. std::pop_heap
, in \(\scriptsize \mathcal{O}(\log N)\)𝓞(log N) time. #include <iostream> #include <algorithm> #include <vector> int main() { std::vector<int> v { 3, 1, 4, 1, 5, 9 }; std::make_heap(v.begin(), v.end()); std::cout << "v: "; for (auto i : v) std::cout << i << ' '; std::cout << '\n'; std::pop_heap(v.begin(), v.end()); // moves the largest to the end std::cout << "after pop_heap: "; for (auto i : v) std::cout << i << ' '; std::cout << '\n'; int largest = v.back(); v.pop_back(); // actually removes the largest element std::cout << "largest element: " << largest << '\n'; std::cout << "heap without largest: "; for (auto i : v) std::cout << i << ' '; std::cout << '\n'; }
Output:
v: 9 5 4 1 1 3 after pop_heap: 5 3 4 1 1 9 largest element: 9 heap without largest: 5 3 4 1 1
adds an element to a max heap (function template) 

(C++11)  checks if the given range is a max heap (function template) 
(C++11)  finds the largest subrange that is a max heap (function template) 
creates a max heap out of a range of elements (function template) 

turns a max heap into a range of elements sorted in ascending order (function template) 

(C++20)  removes the largest element from a max heap (niebloid) 
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