LightOJ -1136 Division by 3 Solution

 Problem Link: https://lightoj.com/problem/division-by-3

Solution in C++: 

///La ilaha illellahu muhammadur rasulullah

///******Bismillahir-Rahmanir-Rahim******///

///Abul Hasnat  Tonmoy

///Department of CSE,23rd batch

///Islamic University,Bangladesh

#include <bits/stdc++.h>

using namespace std;

long long  divisorcount(long long  n)

{

    long long ans;

    ans=(n/3)*2;

    if(n%3==2)

    {

        ans++;

    }

    return ans;

}

int main()

{

    long long  t,n,i=1,a,b;

    cin>>t;

    while(t--)

    {

        cin>>a>>b;

        printf("Case %d: %d\n", i++, divisorcount(b)-divisorcount(a - 1));

    }

    return 0;

}