Check if the number is power of two

Given an Number N, Write a program to check if N is a power of 2.

Approach

Every power of 2 will have only one bit set in it! So, we can use this property to solve this problem.

Example:

N = 16
16 = `10000` in binary

As we can see, there is only one set bit in the binary representation of 16. So, 16 is a power of 2.

When we do N & (N-1) this will be depicted as follows:

16 = 10000
15 = 01111
 
  10000
& 01111
  ------
  00000

So, if the result of N & (N-1) is 0, then the number is a power of 2.

Dry run

Let's take an example to check if N = 16 is a power of 2 or not.

N = 16
16 = 10000
15 = 01111
 
  10000
& 01111
  ------
  00000

Code

boll powerOfTwo(int N) {
    if(N & (N-1) == 0) {
        return true; // return true if N is power of 2
    }
    return false; // else return false
}