std::is_heap_until

 

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all_ofany_ofnone_of (C++11)(C++11)(C++11) for_each countcount_if mismatch equal	findfind_iffind_if_not (C++11) find_end find_first_of adjacent_find search search_n
Modifying sequence operations
copycopy_if (C++11) copy_n (C++11) copy_backward move (C++11) move_backward (C++11) fill fill_n transform generate generate_n removeremove_if remove_copyremove_copy_if	replacereplace_if replace_copyreplace_copy_if swap swap_ranges iter_swap reverse reverse_copy rotate rotate_copy random_shuffleshuffle  (C++11) unique unique_copy
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is_partitioned (C++11) partition partition_copy (C++11)	stable_partition partition_point (C++11)
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is_sorted (C++11) is_sorted_until (C++11) sort	partial_sort partial_sort_copy stable_sort nth_element
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lower_bound upper_bound	binary_search equal_range
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is_heap (C++11) is_heap_until (C++11) make_heap	push_heap pop_heap sort_heap
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C library
qsort	bsearch

 

Defined in header <algorithm>
template< class RandomIt > RandomIt is_heap_until( RandomIt first, RandomIt last );	(1)	(since C++11)
template< class RandomIt, class Compare > RandomIt is_heap_until( RandomIt first, RandomIt last, Compare comp );	(2)	(since C++11)

Examines the range [first, last) and finds the largest range beginning at first which is a max heap. 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 examine
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); The signature does not need to have const &, but the function object must not modify the objects passed to it. The types Type1 and Type2 must be such that an object of type RandomIt can be dereferenced and then implicitly converted to both of them. ​
Type requirements
- RandomIt must meet the requirements of RandomAccessIterator.

Return value

The upper bound of the largest range beginning at first which is a max heap. That is, the last iterator it for which range [first, it) is a max heap.

Complexity

Linear in the distance between first and last

Notes

A max heap is a range of elements [f,l) that has the following properties:

• *f is the largest element in the range
• a new element can be added using std::push_heap()
• the first element can be removed using std::pop_heap()

The actual arrangement of the elements is implementation defined.

Example

Run this code

#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());
 
    // probably mess up the heap
    v.push_back(2);
    v.push_back(6);
 
    auto heap_end = std::is_heap_until(v.begin(), v.end());
 
    std::cout << "all of v: ";
    for (auto i : v) std::cout << i << ' ';
    std::cout << '\n';
 
    std::cout << "only heap: ";
    for (auto i = v.begin(); i != heap_end; ++i) std::cout << *i << ' ';
    std::cout << '\n';
}

Output:

all of v:  9 5 4 1 1 3 2 6 
only heap: 9 5 4 1 1 3 2

See also

is_heap (C++11)

checks if the given range is a max heap (function template)