#include<iostream>
#include<cstdio>
#include<map>
#include<math.h>
#include<queue>
#include<cstring>
#include<algorithm>
using namespace std;
typedef long long ll;
const ll maxn=1e6+7;
ll T,n,a[maxn],pre[maxn],ans;
int main (){
    scanf("%lld",&T);
    while(T--){
         scanf("%lld",&n);
         pre[0]=0;
         ans=0;
         for(int i=0;i<n;i++){
             scanf("%lld",&a[i]);
         }
         sort(a,a+n);
        for(int i=1;i<n;i++){
           pre[i]=pre[i-1]+(a[i]-a[i-1])*(i);
           ans+=pre[i];
        //   printf ("%lld\n",ans);
        }
        printf ("%lld\n",ans);




    }
}