[Leetcode]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.

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class Solution {
public:
/*algorithm
check trailing 0 bit count must even number
*/
bool isPowerOfFour(int num) {
if(num < 1)return false;
while(num%4==0){
num /= 4;
}
return num == 1;
}
};