Codechef Sereja and Array and Subtracting Solution

Solution in C++:
///**********ALLAH IS ALMIGHTY************///
///AH Tonmoy
///Department of CSE,23rd batch
///Islamic University,Bangladesh
#include<iostream>
#include<algorithm>
using namespace std;
int main()
{
    long long int a,i,t,n,v,r;
    cin>>t;
    while(t--)
    {
        cin>>n;
        cin>>a;
        r=a;
        for(i=1;i<n;i++)
        {
            cin>>v;
            r=__gcd(r,v);
        }
        cout<<r*n<<endl;
    }

}