Given an integer, write a function to determine if it is a power of three.
Follow up:
Could you do it without using any loop / recursion?
class Solution(object): def isPowerOfThree(self, n): """ :type n: int :rtype: bool """ #method 1 return n > 0 and 3 ** round(math.log(n,3)) == n #method 2 if n < 0: return False if n == 0: return False re = math.log(n) / math.log(3.0) i = round(re,0) if abs(re-i) < 1e-10: return True else: return False