#include <stdio.h>
#include <algorithm>
#define MN 200000
typedef long long LL;

int n,a[MN+5];
LL ans,tans;

void solve(){
    scanf("%d",&n);
    for(int i=1;i<=n;i++)
        scanf("%d",&a[i]);
    std::sort(a+1,a+1+n);
    tans = ans = 0;
    for(int i=2;i<=n;i++){
        tans += 1ll*(a[i]-a[i-1])*(i-1);
        ans += tans;
    }
    printf("%lld\n",ans);
}

int main(){
    int T; scanf("%d",&T);
    while(T--) solve();
}