message: update power-of-three.py
  add another solution for 'Power of Three' based on The Change-of-Base Formula
diff: @@ -20,3 +20,8 @@ class Solution(object):
  :rtype: bool
  """
  return n > 0 and self.__max_pow3 % n == 0
  +
  +
  +class Solution2(object):
  + def isPowerOfThree(self, n):
  + return n > 0 and (math.log10(n)/math.log10(3)).is_integer()
  