Ugly Number

题目描述

Write a program to check whether a given number is an ugly number.

Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 6, 8 are ugly while 14 is not ugly since it includes another prime factor 7.

Note that 1 is typically treated as an ugly number.

解题方法

• 如果number能被2,3或者5整除，那么就除以可以整除的
• 如果不能被2，3，5中的一个整除，说明不是ugly number
• ugly number应该可以一直被除到1，此时可以结束说明是ugly number

Solution

class Solution(object):
    def isUgly(self, num):
        """
        :type num: int
        :rtype: bool
        """
        if num < 1:
            return False
        while num != 1:
            if num % 2 == 0:
                num /= 2
            elif num % 3 == 0:
                num /= 3
            elif num % 5 == 0:
                num /= 5
            else:
                return False
        return True

Reference