poj Fence Repair 贪心

#include <iostream>  
#include <cstdio>  
#include <cstring>  
#include <queue>  
#define ll long long  
using namespace std;  
const int maxn=2e4+9;  
  
int main()  
{  
    int n;  
    priority_queue <ll,vector<ll>,greater<ll> > q;  
    while(scanf("%d",&n)!=EOF)  
    {  
        while(!q.empty()) q.pop();  
        for(int i=1,tmp;i<=n;i++)  
        {  
            scanf("%d",&tmp);  
            q.push(tmp);  
        }  
        long long ans=0;  
        for(int i=1;i<n;i++)  
        {  
            long long tmp=0;  
            tmp+=q.top(),q.pop();  
            tmp+=q.top(),q.pop();  
            ans+=tmp;  
            q.push(tmp);  
        }  
        cout<<ans<<endl;  
    }  
    return 0;  
}