#include "bits/stdc++.h"
using ll = long long;
using namespace std;

int main() {
   int t;
   cin>>t;
   while(t-->0)
   {
    ll n;
    cin>>n;
    vector<ll>a(n);
    for(ll i=0;i<n;++i)
    {
        cin>>a[i];
    }
    sort(a.begin(),a.end());
    ll maxnum = 0;
    for(ll i=0;i<n-1;++i)
    {
        ll c = a[i+1]-a[i];
        maxnum = max(maxnum,c*(n-i-1));
    }
    maxnum = max(maxnum,a[0]*n);
    cout<<maxnum<<endl;
   } 
}
// 64 位输出请用 printf("%lld")