UVA 11054 Gergovia的酒交易 Wine trading in Gergovia

#include<bits/stdc++.h>
using namespace std;
int n;
int main(){
    while(~scanf("%d",&n)&&n){
        long long a,ans=0,last=0;//不开LL见祖宗
        for(int i=1;i<=n;i++){
            scanf("%lld",&a);
            ans+=abs(last);//取绝对值是因为劳动力为正
            last+=a;//加上这一次的劳动力
        }
        printf("%lld\n",ans);
    }
}