Power of Four

Given an integer (signed 32 bits), write a function to check whether it is a power of 4.

Example: Given num = 16, return true. Given num = 5, return false.

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

Credits:Special thanks to @yukuairoy for adding this problem and creating all test cases.

Solution

public class Solution {
    public boolean isPowerOfFour(int num) {
        if(num == 0) return false;

        while (num != 1) {
            if (num % 4 != 0) {
                return false;
            }

            num /= 4;
        }

        return true;
    }
}