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