Power of Four
Given an integer n, return true if it is a power of four. Otherwise, return false.
An integer n is a power of four if there exists an integer x such that n == 4^x.
Follow up: Could you solve it without loops/recursion?
Example 1
Input
n = 16Output
trueSince 16 equals 4^2, it is a power of four.
Example 2
Input
n = 5Output
falseThere is no integer x such that 5 equals 4^x.
Constraints
- -2^31 <= n <= 2^31 - 1