sort_heap sort_heap Category: algorithms Component type: function Prototype Sort_heap is an overloaded name; there are actually two sort_heap functions. template <class RandomAccessIterator> void sort_heap(RandomAccessIterator first, RandomAccessIterator last); template <class RandomAccessIterator, class StrictWeakOrdering> void sort_heap(RandomAccessIterator first, RandomAccessIterator last, StrictWeakOrdering comp); Description Sort_heap turns a heap [1] [first, last) into a sorted range. Note that this is not a stable sort: the relative order of equivalent elements is not guaranteed to be preserved. The two versions of sort_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. Definition Defined in the standard header algorithm, and in the nonstandard backward-compatibility header algo.h. Requirements on types For the first version, the one that takes two arguments: 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, the one that takes three arguments: 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, the one that takes two arguments: [first, last) is a valid range. [first, last) is a heap. That is, is_heap(first, last) is true. For the second version, the one that takes three arguments: [first, last) is a valid range. [first, last) is a heap. That is, is_heap(first, last, comp) is true. Complexity At most N * log(N) comparisons, where N is last - first. Example int main() { int A[] = {1, 4, 2, 8, 5, 7}; const int N = sizeof(A) / sizeof(int); make_heap(A, A+N); copy(A, A+N, ostream_iterator<int>(cout, " ")); cout << endl; sort_heap(A, A+N); copy(A, A+N, ostream_iterator<int>(cout, " ")); cout << endl; } 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 push_heap, pop_heap, make_heap, is_heap, sort, stable_sort, partial_sort, partial_sort_copy Copyright © 1999 Silicon Graphics, Inc. All Rights Reserved. TrademarkInformation