342. Power of Four（LeetCode）

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?

 1 class Solution {
 2 public:
 3     bool isPowerOfFour(int num) {
 4          if (num == 0)
 5             return false;
 6         while (num != 1)
 7         {
 8             if (num % 4 != 0)
 9                 break;
10             else
11             {
12                 num = num / 4;
13             }
14         }
15         if (num == 1)
16             return true;
17         else
18             return false;
19     }
20 };