leetcode-342-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?

给定一个32位的整数，判断它是否是4的幂。

class Solution {
public:
    bool isPowerOfFour(int num) {
        while(num>1&&num%4==0)
        {
            num/=4;
        }
        return num==1;
    }
};