Power of Three

Solution 1

def isPowerOfThree(self, n):
    """
    :type n: int
    :rtype: bool
    """
    if n <= 0:
        return False
    while n != 1:
        if n % 3 != 0:
            return False
        n /= 3
    return True

Solution 2 - Direct

def isPowerOfThree(self, n):
    """
    :type n: int
    :rtype: bool
    """
    # 1162261467 is 3^19,  3^20 is bigger than int  
    return  n>0 and 1162261467%n==0

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