排序算法之堆排序

#include <iostream>
using namespace std;

void AdjustHeap(int a[], int begin, int end, int pos)
{
	int lchild = 2 * pos - begin + 1;
	int rchild = 2 * pos - begin + 2;
	int TracePos = -1;
	if(lchild > end)
		return;
	if(rchild <= end)
		a[lchild] > a[rchild]? TracePos = lchild : TracePos = rchild;
	else if(lchild <= end)
		TracePos = lchild;

	if(a[pos] < a[TracePos]) 
	{
		swap(a[pos], a[TracePos]);
		AdjustHeap(a, begin, end, TracePos);
	}
}

void HeapSort(int a[], int begin, int end)
{
	int len = end - begin + 1;
	for(int i = begin + (len / 2 - 1); i >= begin; --i)
		AdjustHeap(a, begin, end, i);

	for(int i = end; i >= begin; --i)
	{
		AdjustHeap(a, begin, i, begin);
		swap(a[begin], a[i]);
	}
}

int main()
{
	int a[] = {2334, 12112121, 1212, 45, 45, 12, 34343};
	//int a[] = {};
	int len = sizeof(a)/sizeof(int);
	random_shuffle(a, a + len);
	HeapSort(a, 0, len - 1);
	for(int i = 0; i < len; ++i)
		cout<< a[i] << " ";
}