堆排序

#include <iostream>
#include <algorithm>
using namespace std;
const int N = 100010;
int h[N],size1;
void down(int u)
{
	int t = u;
	if (2 * u <= size1 && h[2 * u] < h[t]) t = 2 * u;
	if (2 * u + 1 <= size1 && h[2 * u + 1] < h[t]) t = 2 * u + 1;
	if (t != u)
		swap(h[u], h[t]), down(t);
}
int main()
{
	int n;cin >> n;
	for (int i = 1;i <= n;i++) cin >> h[i];
	size1 = n;
	for (int i = n >>1;i;i--) down(i);
	cout << "\n排序后：";
	for (int i = 0;i < n;i++)
	{
		cout << h[1] << " ";
		h[1] = h[size1--];
		down(1);
	}
	return 0;
}

Run

输入：

5

5 4 3 2 1

输出：

1 2 3 4 5