std::is_heap_until

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Defined in header <algorithm>

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template< class RandomAccessIterator >

RandomAccessIterator is_heap_until( RandomAccessIterator first,

                                    RandomAccessIterator last );

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template< class RandomAccessIterator, class Compare >

RandomAccessIterator is_heap_until( RandomAccessIterator first,
                                    RandomAccessIterator last,

                                    Compare comp );

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Examines the range [first, last) and finds the largest range beginning at first which is heap. The first version of the function uses Template:cpp 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); 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) Type1 and Type2 regardless of value category (thus, Type1& is not allowed, nor is Type1 unless for Type1 a move is equivalent to a copy(since C++11)). The types Type1 and Type2 must be such that an object of type RandomAccessIterator can be dereferenced and then implicitly converted to both of them.

Return value

The upper bound of the largest range beginning at first which is heap. That is, the last iterator {{tt|it}] for which range [first, it) is heap.

Complexity

linear in the distance between first and last

Notes

A heap with respect to comp (max heap) is a random access range [first, last) that has the following properties:

• Given \(\scriptsize N\)N as last - first, for all integer i where \(\scriptsize 0 < i < N\)0 < i < N, bool(comp(first[(i - 1) / 2], first[i])) is false.
• A new element can be added using std::push_heap, in \(\scriptsize \mathcal{O}(\log N)\)𝓞(log N) time.
• *first can be removed using std::pop_heap, in \(\scriptsize \mathcal{O}(\log N)\)𝓞(log N) time.

See also

Template:cpp/algorithm/dcl list is heap