以 codevs1076 排序為例；
手打堆：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <queue>
using namespace std;

const int MAXN = 100000 + 10;
int n, cnt = 0;
int heap[MAXN];

void push(int x)
{
    heap[++cnt] = x;
    int now = cnt;
    while(now >= 1)
    {
        int
 
 fa = now/2;
        if(heap[fa] > heap[now])
        {
            swap(heap[fa], heap[now]);
            now /= 2;
        }
        else break;
    }
}

void pop()
{
    heap[1] = heap[cnt];
    cnt --;
    int now = 1;
    while(now*2 <= cnt)
    {
        int l = now*2, r = now*2+1;
        if
 
(heap[l] < heap[now])
        {
            if(heap[r] < heap[now] && heap[r] < heap[l])
                swap(l,r);
            swap(heap[l], heap[now]);
            now = l;
        }
        else if(heap[r] < heap[now])
        {
            swap(heap[r], heap[now]);
            now = r;
        }
        else
 
 break;
    }
}

int main()
{
    cin >> n;
    for(int i = 1; i <= n; i ++)
    {
        int t;
        scanf("%d", &t);
        push(t);
    }
    while(n --)
    {
        printf("%d ", heap[1]);
        pop();
    }
    return 0;
}

priority_queue 加過載。
記得 priority 是預設大根堆並且內部用 < 排序， 所以需要過載 < 為 > 而不是 過載 > 為 <;

#include <cstdio>
#include <queue>
#include <cstring>
#include <iostream>
using namespace std;

struct T{
    int a;
};

priority_queue <T> q;
bool operator < (T a, T b)
{
    return a.a > b.a;
} 

int main()
{
    int n;
    cin >> n;
    for(int i = 1; i <= n; i++)
    {
        int t;
        scanf("%d",&t);
        q.push((T){t});
    }
    while(q.size())
    {
        printf("%d ", q.top().a);
        q.pop();
    }
    return 0;
}