CodeChef Starters 31 Division 3 (Rated) The Unchanging OR Problem Code: UNCHANGEDOR Solution

Problem Link:   https://www.codechef.com/START31C/problems/UNCHANGEDOR

 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;

int main()

{

    long long n,x,t,cn,a,s,r;

    cin>>t;

    while(t--)

    {

        x=0;

        cin>>n;

        cn=n;

        if(n==2)

            cout<<"0"<<endl;

        else if(n==3||n==4)

            cout<<"1"<<endl;

        else

        {

            for(int i=1; i<=50; i++)

            {

                s=pow(2,i);

                x++;

                if(s>n)

                    break;

            }

            x--;

            a=cn-(pow(2,x));

            r=(pow(2,x)-x-1);

            if(a==0)

            {

                cout<<r<<endl;

            }

            else

            {

                cout<<r+a<<endl;

            }

        }

    }

}