Minimum number using set bits of a given number in C++

Problem statement

Given an unsigned number, find the minimum number that could be formed by using the bits of the given unsigned number.

Example

If input = 10 then answer would be 3

Binary representation of 10 is 1010 and minimum number with 2 set bits is 0011 i.e. 3

Algorithm

1. Count the number of set bits.
2. (Number of set bits) ^ 2 – 1 represents the minimized number)

Example

 Live Demo

#include <bits/stdc++.h>
using namespace std;
int getSetBits(int n) {
   int cnt = 0;
   while (n) {
      ++cnt;
      n = n & (n - 1);
   }
   return cnt;
}
int getMinNumber(int n){
   int bits = getSetBits(n);
   return pow(2, bits) - 1;
}
int main() {
   int n = 10;
   cout << "Minimum number = " << getMinNumber(n) << endl;
   return 0;
   return 0;
}

When you compile and execute above program. It generates following output

Output

Minimum number = 3