231. Power of Two

 Given an integer n, return true if it is a power of two. Otherwise, return false.

An integer n is a power of two, if there exists an integer x such that n == 2x.

 

Example 1:

Input: n = 1
Output: true
Explanation: 20 = 1

Example 2:

Input: n = 16
Output: true
Explanation: 24 = 16

Example 3:

Input: n = 3
Output: false

 

Constraints:

• -231 <= n <= 231 - 1

 

Follow up: Could you solve it without loops/recursion?

Solution:

In JS:

var isPowerOfTwo = function(n) {

    if (n <= 0) {

        return false;

    }

    while (n != 1) {

        if(n % 2 == 1) {

            return false;

        }

        n /= 2;

    }

    return true;

};