#include<iostream>
#include<cmath>
#include<cstdio>
#include<string>
#include<cstring>
#include<algorithm>
#define ll long long
using namespace std;

ll int a[101000]={0},n,t;
int main(){
    cin>>t;
    for(int ti=1;ti<=t;ti++){
        cin>>n;
        
        for(int i=1;i<=n;i++){
            //cin>>a[i];
            scanf("%lld",&a[i]);
        }if(n==1){
            cout<<0<<endl;continue;
        }
        sort(a+1,a+1+n);
        ll ans=0,x=0;
        for(ll int i=2;i<=n;i++){
            ll int tem=a[i]-a[i-1];
            x=x+tem*(i-1);
            ans+=x;    
        }
        cout<<ans<<endl;
    }
    
    return 0;
}