totalSetBits.cpp

https://www.geeksforgeeks.org/problems/count-total-set-bits-1587115620/1

// good question :- TLE 
//{ Driver Code Starts
//Initial Template for C++

#include<bits/stdc++.h>
using namespace std;


// } Driver Code Ends
//User function Template for C++

class Solution{
    private:
    int setBits(int n) {
    int count = 0;
    while (n > 0) {
        if (n % 2 == 1) {
            count++;
        }
        n = n / 2;
    }
    return count;
}
    public:
    // n: input to count the number of set bits
    //Function to return sum of count of set bits in the integers from 1 to n.
    int countSetBits(int N)
    {
       int totalBits = 0;
    for (int i = 0; i <= N; i++) {
        totalBits += setBits(i);
    }
    return totalBits;
    }


};


//{ Driver Code Starts.

// Driver code
int main()
{
	 int t;
	 cin>>t;// input testcases
	 while(t--) //while testcases exist
	 {
	       int n;
	       cin>>n; //input n
	       Solution ob;
	       cout << ob.countSetBits(n) << endl;// print the answer
	  }
	  return 0;
}

// } Driver Code Ends