本题考查STL优先队列的使用。见:http://blog.youkuaiyun.com/return___0/article/details/79220803
关键的写法是:
priority_queue<int,vector<int>,less<int> >q;
priority_queue<int,vector<int>,greater<int>
>q;
其中,less是从大到小,greater是从小到大。
AC代码:
#include <cstdio>
#include <queue>
using namespace std;
int main()
{
int t;
scanf("%d",&t);
while(t--)
{
priority_queue< long long,vector<long long>,greater<long long> > q;
int n,num;
long long x,y;
scanf("%d",&n);
long long ans=0;
for(int i=0;i<n;i++)
{
scanf("%d",&num);
q.push(num);
}
while(q.size()!=1)
{
x=q.top();
q.pop();
y=q.top();
q.pop();
ans=ans+x+y;
q.push(x+y);
}
printf("%lld\n",ans);
}
return 0;
}