Largest Number with Binary Representation: m-1's and m-1 0's in C++

In this tutorial, we are going to write a program that finds the largest number with m 1's and m - 1 0's.

Let's see the steps to solve the problem.

• Initialise two variables bits and result with 2 and 1 respectively.
• Write a loop that iterates from 1 to n.
  • Update the iterating variable value with pow(2, bits) - 1) * (pow(2, bits - 1).
  • If the iterative variable is less than n, then update the result with i.
  • Increment the bits count.
• Return resutl.

Example

Let's see the code.

 Live Demo

#include <bits/stdc++.h>
using namespace std;
long long getTheNumber(long long n) {
   long bits = 2;
   long long result = 1;
   long long i = 1;
   while (i < n) {
      i = (int)(pow(2, bits) - 1) * (pow(2, bits - 1));
      if (i < n) {
         result = i;
      }
      bits++;
   }
   return result;
}
int main() {
   long long n = 654;
   cout << getTheNumber(n) << endl;
   return 0;
}

Output

If you run the above code, then you will get the following result.

496

Conclusion

If you have any queries in the tutorial, mention them in the comment section.