51nod 1117 聪明的木匠 (哈夫曼树)

#include <iostream>
#include <cstdio>
#include <cmath>
#include <queue>
#include <algorithm>
using namespace std;
struct cmp
{
    bool operator ()(long long &a,long long &b)
    {
        return a>b;
    }
};
int main()
{
    long long n,a,b,sum;
    while(cin>>n)
    {
        sum=0;
        priority_queue<long long,vector<long long>,cmp>q;
        while(n--)
        {
            cin>>a;
            q.push(a);
        }
        while(q.size()>1)
        {
            a=q.top();
            q.pop();
            b=q.top();
            q.pop();
            sum=sum+a+b;
            q.push(a+b);
        }
        cout<<sum<<endl;
    }
    return 0;
}