# 326. Power of Three
"""
given an integer 'n', return true if it is a power of three. otherwise,
return false. an integer 'n' is a power of three, if there exists an integer
'x' such that 'n == 3^x'
"""
class Solution(object):
def isPowerOfThree(self, n):
"""
the positive divisors of 3^19 are exactly the powers of 3
from 3^0 to 3^19. that's all powers of 3 in the possible range
here (signed 32-bit integer). so check whether the number is
positive and whether it divides 3^19
"""
return n > 0 == 3**19 % n
if __name__ == "__main__":
obj = Solution()
print(obj.isPowerOfThree(27))
print(obj.isPowerOfThree(0))
print(obj.isPowerOfThree(-1))
