优先队列

排序从大到小

priority_queue<int,vector<int>,greater<int> >q;

堆排序

#include <iostream>
#include <algorithm>

using namespace std;

const int N = 100010;

int n, m;
int h[N], cnt;

void down(int u)
{
    int t = u;
    if (u * 2 <= cnt && h[u * 2] < h[t]) t = u * 2;
    if (u * 2 + 1 <= cnt && h[u * 2 + 1] < h[t]) t = u * 2 + 1;
    if (u != t)
    {
        swap(h[u], h[t]);
        down(t);
    }
}

int main()
{
    scanf("%d%d", &n, &m);
    for (int i = 1; i <= n; i ++ ) scanf("%d", &h[i]);
    cnt = n;

    for (int i = n / 2; i; i -- ) down(i);//从2/n 建堆 

    while (m -- )
    {
        printf("%d ", h[1]);//输出对顶
        h[1] = h[cnt -- ];//交换
        down(1);//下降
    }

    puts("");

    return 0;
}