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?
public class Solution { public boolean isPowerOfFour(int num) { int n=num; while(n>0&&n%4==0){ n/=4; } return n==1; //return (num > 0) && ((num & (num - 1)) == 0) && ((num & 0x55555555) == num); } }