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?

注意 0 1 这两个值

class Solution {public:    bool isPowerOfFour(int num) {        if(num==0)return false;        if(num==1)return true;        if(num%4==0){            if(num==4)return true;        else{            return isPowerOfFour(num/4);        }        }else{            return false;        }    }};