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std::ranges::pop_heap

From cppreference.com
< cpp‎ | algorithm‎ | ranges
 
 
Algorithm library
Constrained algorithms, e.g. ranges::copy, ranges::sort, ...
(C++11)
(C++11)
(C++17)

 
Constrained algorithms
All names in this menu belong to namespace std::ranges
       
       
    
     
         
pop_heap
       
       
(C++23)
(C++23)  
(C++23)
(C++23)  
(C++23)            
 
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 pop_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>

    pop_heap( R&& r, Comp comp = {}, Proj proj = {} );
(2) (since C++20)

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.

1) The specified heap is [firstlast).
2) The specified heap is r.

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

[edit] 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

[edit] Return value

1) last

[edit] 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:

1) ranges::distance (first, last)

[edit] 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 ]

[edit] See also

adds an element to a max heap
(algorithm function object)[edit]
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]
turns a max heap into a range of elements sorted in ascending order
(algorithm function object)[edit]
removes the largest element from a max heap
(function template) [edit]
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