poj 2231 Moo Volume

#include<cstdio>#include<cstring>#include<algorithm>using namespace std;long long int d[10010];int main(){int n;scanf("%d",&n); for(int i=0;i<n;i++)scanf("%lld",&d[i]);sort(d,d+n);long long int res=0;long long int now=d[0];for(int i=1;i<n;i++){res+=d[i]*i-now;now+=d[i];} printf("%lld\n",res*2);return 0;}