std::sort_heap
Defined in header <algorithm>
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template< class RandomIt > void sort_heap( RandomIt first, RandomIt last ); |
(1) | (constexpr since C++20) |
template< class RandomIt, class Compare > void sort_heap( RandomIt first, RandomIt last, Compare comp ); |
(2) | (constexpr since C++20) |
Converts the heap [
first,
last)
into a sorted range. The heap property is no longer maintained.
If any of the following conditions is satisfied, the behavior is undefined:
-
[
first,
last)
is not a heap.
|
(until C++11) |
|
(since C++11) |
Contents |
[edit] Parameters
first, last | - | the heap to be sorted |
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: bool cmp(const Type1& a, const Type2& b); While the signature does not need to have const&, the function must not modify the objects passed to it and must be able to accept all values of type (possibly const) |
Type requirements | ||
-RandomIt must meet the requirements of LegacyRandomAccessIterator.
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-Compare must meet the requirements of Compare.
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[edit] Complexity
Given N as std::distance(first, last):
[edit] Possible implementation
sort_heap (1) |
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template<class RandomIt> void sort_heap(RandomIt first, RandomIt last) { while (first != last) std::pop_heap(first, last--); } |
sort_heap (2) |
template<class RandomIt, class Compare> void sort_heap(RandomIt first, RandomIt last, Compare comp) { while (first != last) std::pop_heap(first, last--, comp); } |
[edit] Example
#include <algorithm> #include <iostream> #include <string_view> #include <vector> void println(std::string_view fmt, const auto& v) { for (std::cout << fmt; const auto &i : v) std::cout << i << ' '; std::cout << '\n'; } int main() { std::vector<int> v{3, 1, 4, 1, 5, 9}; std::make_heap(v.begin(), v.end()); println("after make_heap, v: ", v); std::sort_heap(v.begin(), v.end()); println("after sort_heap, v: ", v); }
Output:
after make_heap, v: 9 4 5 1 1 3 after sort_heap, v: 1 1 3 4 5 9
[edit] Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR | Applied to | Behavior as published | Correct behavior |
---|---|---|---|
LWG 2444 | C++98 | at most N⋅log(N) comparisons were allowed | increased to 2N⋅log(N) |
[edit] See also
(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) | |
removes the largest element from a max heap (function template) | |
adds an element to a max heap (function template) | |
(C++20) |
turns a max heap into a range of elements sorted in ascending order (algorithm function object) |