#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
typedef long long ll;
const int maxn=100010;
int test,n;
ll a[maxn],ans;

int main(){
    scanf("%d",&test);
    while(test--)
    {
        scanf("%d",&n);
        ans=0;
        for(int i=0;i<n;i++)scanf("%lld",a+i);
        sort(a,a+n);
        ll tmp=0;//i-1
        for(int i=1;i<n;i++){
            tmp=(a[i]-a[i-1])*i+tmp;
            ans+=tmp;
        }
        printf("%lld\n",ans);
    }
    
    return 0;
}