std::sort_heap
std::sort_heap
Defined in header <algorithm> | ||
---|---|---|
template< class RandomIt > void sort_heap( RandomIt first, RandomIt last ); | (1) | |
template< class RandomIt, class Compare > void sort_heap( RandomIt first, RandomIt last, Compare comp ); | (2) |
Converts the max heap [first, last)
into a sorted range in ascending order. The resulting range no longer has the heap property.
The first version of the function uses operator<
to compare the elements, the second uses the given comparison function comp
.
Parameters
first, last | - | the range of elements to sort |
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:
The signature does not need to have |
Type requirements | ||
-RandomIt must meet the requirements of ValueSwappable and RandomAccessIterator . |
||
-The type of dereferenced RandomIt must meet the requirements of MoveAssignable and MoveConstructible . |
Return value
(none).
Complexity
At most N×log(N) comparisons where N=std::distance(first, last)
.
Notes
A max heap is a range of elements [f,l)
that has the following properties:
- With
N = l - f
, for all0 < i < N
,f[floor(
does not compare less thani-1 2 f[i]
. - a new element can be added using
std::push_heap()
- the first element can be removed using
std::pop_heap()
Possible implementation
First version |
---|
template< class RandomIt > void sort_heap( RandomIt first, RandomIt last ); { while (first != last) std::pop_heap(first, last--); } |
Second version |
template< class RandomIt, class Compare > void sort_heap( RandomIt first, RandomIt last, Compare comp ); { while (first != last) std::pop_heap(first, last--, comp); } |
Example
#include <algorithm> #include <vector> #include <iostream> int main() { std::vector<int> v = {3, 1, 4, 1, 5, 9}; std::make_heap(v.begin(), v.end()); std::cout << "heap:\t"; for (const auto &i : v) { std::cout << i << ' '; } std::sort_heap(v.begin(), v.end()); std::cout << "\nsorted:\t"; for (const auto &i : v) { std::cout << i << ' '; } std::cout << '\n'; }
Output:
heap: 9 4 5 1 1 3 sorted: 1 1 3 4 5 9
See also
creates a max heap out of a range of elements (function template) |
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