342. Power of Four

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

Example 1:

Input: 16
Output: true 

Example 2:

Input: 5
Output: false

class Solution {
    public boolean isPowerOfFour(int num) {
         return Math.log10(num) / Math.log10(4) % 1 == 0; 
    }
}