堆排序

 

void AdjustHeap(int a[],int rootIndex,int maxIndex)
{
	if (rootIndex > maxIndex)
	{
		return;
	}
	int lChild = 2 * rootIndex + 1;
	int rChild = 2 * rootIndex + 2;

	int index = rootIndex;
	if (lChild <= maxIndex && a[index] < a[lChild]) index = lChild;
	if (rChild <= maxIndex && a[index] < a[rChild]) index = rChild;
	
	if ( index != rootIndex)
	{
		int temp = a[index];
		a[index] = a[rootIndex];
		a[rootIndex] = temp;

		AdjustHeap(a,index,maxIndex);
	}
}


void HeapSort(int a[],int n)
{
	int i = ( n - 2 )/2;
	for (;i>= 0;--i)
	{
		AdjustHeap(a,i,n-1);
	}

	for (i = 0; i < n;++i)
	{
		int temp = a[0];
		a[0] = a[n-1-i];
		a[n-1-i] = temp;
		AdjustHeap(a,0,n-2-i);
	}
}