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# Ugly Number

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.

## 题目大意：

编写程序判断一个给定的数字是否为“丑陋数” ugly number

丑陋数是指只包含质因子2, 3, 5的正整数。例如，6, 8是丑陋数而14不是，因为它包含额外的质因子7

注意，数字1也被视为丑陋数

## 解题思路：

将输入数重复除2, 3, 5，判断得数是否为1即可

时间复杂度：

记`num = 2^a * 3^b * 5^c * t`，程序执行次数为`a + b + c`，换言之，最坏情况为`O(log num)`

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