数据结构-排序-堆排序

堆排序

升序建大堆
降序建小堆

复杂度
O(N*logN)

void AdjustDwon(int * a, int n, int root)
{
	int child = root * 2 + 1;
	while (child < n)
	{
		if (child + 1 < n && a[child + 1] > a[child])
		{
			++child;
		}
		if (a[child] > a[root])
		{
			Swap(&a[child], &a[root]);
			root = child;
			child = root * 2 + 1;
		}
		else
		{
			break;
		}
	}
}
void HeapSort(int * a, int n)
{
	//建堆
	for (int i = (n - 1 - 1) / 2; i >= 0; i--)
	{
		AdjustDwon(a, n, i);
	}
	int end = n - 1;
	while (end > 0)
	{
		Swap(&a[0], &a[end]);
		AdjustDwon(a, end, 0);
		--end;
	}
}