Standard C++ Library Class Reference

Description

A heap is a particular organization of elements in a range between two random access iterators

[a, b). Its two key properties are:

*a is the largest element in the range.1.

*a may be removed by pop_heap(), or a new element added by push_heap(), in O(logN)

time.

These properties make heaps useful as priority queues.

The sort_heap algorithm converts a heap into a sorted collection over the range [first, last)

using either the default operator (<) or the comparison function supplied with the algorithm.

Note that sort_heap is not stable, i.e., the elements may not be in the same relative order after

sort_heap is applied.

Complexity

sort_heap performs at most NlogN comparisons where N is equal to last - first.

Example

// heap_ops.cpp

#include <algorithm>

#include <vector>

#include <iostream.h>

int main(void)

{

int d1[4] = {1,2,3,4};

int d2[4] = {1,3,2,4};

// Set up two vectors

vector<int> v1(d1,d1 + 4), v2(d2,d2 + 4);

// Make heaps

make_heap(v1.begin(),v1.end());

make_heap(v2.begin(),v2.end(),less<int>());

// v1 = (4,x,y,z) and v2 = (4,x,y,z)

// Note that x, y and z represent the remaining

// values in the container (other than 4).

// The definition of the heap and heap operations

// does not require any particular ordering

// of these values.

// Copy both vectors to cout

ostream_iterator<int> out(cout," ");