Definition Defined in the standard header algorithm, and in the nonstandard backward-compatibility header algo.h.
Requirements on types For the first version:
• RandomAccessIterator is a model of Random Access Iterator.
• RandomAccessIterator is mutable.
• RandomAccessIterator's value type is a model of LessThan Comparable.
• The ordering on objects of RandomAccessIterator's value type is a strict weak ordering, as defined in the LessThan Comparable requirements.
For the second version:
• RandomAccessIterator is a model of Random Access Iterator.
• RandomAccessIterator is mutable.
• StrictWeakOrdering is a model of Strict Weak Ordering.
• RandomAccessIterator's value type is convertible to StrictWeakOrdering's argument type.
Preconditions For the first version:
• [first, last) is a valid range.
• [first, last – 1) is a valid range. That is, [first, last) is nonempty.
• [first, last – 1) is a heap. That is, is_heap(first, last – 1) is true.
For the second version:
• [first, last) is a valid range.
• [first, last – 1) is a valid range. That is, [first, last) is nonempty.
• [first, last) is a heap. That is, is_heap(first, last – 1, comp) is true.
Complexity Logarithmic. At most log(last – first) comparisons.
Example int main() {
int A[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
make_heap(A, A + 9);
cout << '[A, A + 9) = ';
copy (A, A + 9, ostream_iterator<int>(cout, ' '));
push_heap(A, A + 10);
cout << endl << '[A, A + 10) = ';
copy (A, A + 10, ostream_iterator<int>(cout, ' '));
cout << endl;
}
The output is
[A, A + 9) = 8 7 6 3 4 5 2 1 0
[A, A + 10) = 9 8 6 3 7 5 2 1 0 4
Notes
[1] A heap is a particular way of ordering the elements in a range of random access iterators [f, l). The reason heaps are useful (especially for sorting, or as priority queues) is that they satisfy two important properties. First, *f is the largest element in the heap. Second, it is possible to add an element to a heap (using push_heap), or to remove *f, in logarithmic time. Internally, a heap is a tree represented as a sequential range. The tree is constructed so that that each node is less than or equal to its parent node.
See also make_heap, pop_heap, sort_heap, is_heap, sort
Category: algorithms
Component type: function
Prototype Pop_heap is an overloaded name; there are actually two pop_heap functions.
template <class RandomAccessIterator>
void pop_heap(RandomAccessIterator first, RandomAccessIterator last);
template <class RandomAccessIterator, class StrictWeakOrdering>
inline void pop_heap(RandomAccessIterator first, RandomAccessIterator last, StrictWeakOrdering comp);
Description Pop_heap removes the largest element (that is, *first ) from the heap [1] [first, last). The two versions of pop_heap differ in how they define whether one element is less than another. The first version compares objects using operator<, and the second compares objects using a function object comp.
The postcondition for the first version of pop_heap is that is_heap (first, last-1) is true and that *(last – 1) is the element that was removed from the heap. The postcondition for the second version is that is_heap (first, last-1, comp) is true and that *(last – 1) is the element that was removed from the heap. [2]
Definition Defined in the standard header algorithm, and in the nonstandard backward-compatibility header algo.h.
Requirements on types For the first version:
• RandomAccessIterator is a model of Random Access Iterator.
• RandomAccessIterator is mutable.
• RandomAccessIterator's value type is a model of LessThan Comparable.
• The ordering on objects of RandomAccessIterator's value type is a strict weak ordering, as defined in the LessThan Comparable requirements.
For the second version:
• RandomAccessIterator is a model of Random Access Iterator.
• RandomAccessIterator is mutable.
• StrictWeakOrdering is a model of Strict Weak Ordering.
• RandomAccessIterator's value type is convertible to StrictWeakOrdering's argument type.
Preconditions For the first version:
