Big Big mod

Here divisor is integer but the number is very very big number. Then it will work. This is the solution of LightOJ problem Link : Click Here.

 #include<iostream>

using namespace std;

int main(){

    int T;

    cin>>T;

    for(int tc=1;tc<=T;tc++){

        string a;

        long long b;

        cin>>a>>b;

        if(b<0){

            b*=-1;

        }

        int p=0;

        if(a[0]=='-'){

            p=1;

        }

        long long sub=0;

        while(p<a.size()){

            if(sub>=b){

                sub=sub%b;

            }

            sub*=10;

            sub+=(a[p]-'0');

            p++;

            //cout<<sub<<endl;

        }

        sub=sub%b;

        if(sub){

            cout<<"Case "<<tc<<": not divisible"<<endl;

        }else{

            cout<<"Case "<<tc<<": divisible"<<endl;

        }

    }return 0;

}