Point:

优先队列定义
小根堆 priority_queue<int, vector<int>, greater<int>> heap;
大根堆 priority_queue<int, vector<int>, less<int>> heap;

基本操作

 heap.push();   // 入队
 heap.pop();    // 出队
 heap.size();   // 元素个数
 heap.top();    // 队首
 heap.empty();  // 判空

C++ 代码

#include <iostream>
#include <queue>
using namespace std;
#define int long long
#define p_qi priority_queue<int, vector<int>, less<int>>
signed main()
{
    int n;
    cin >> n;
    p_qi heap;
    for(int i = 1; i <= n; ++ i)
    {
        int temp;
        scanf("%lld",&temp);
        heap.push(temp);
    }
    int res = 0;
    while(heap.size() > 1)
    {
        int a = heap.top(); heap.pop();
        int b = heap.top(); heap.pop();
        res += a + b;
        heap.push(a + b);
    }

    printf("%lld\n", res);
    return 0;
}