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:
The signature does not need to have |
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
#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
(C++11) | checks if the given range is a max heap (function template) |
std::experimental::parallel::is_heap_until
(parallelism TS) | parallelized version of std::is_heap_until (function template) |
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