leetcode 263. 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.

Example 1:

Input: 6
Output: true
Explanation: 6 = 2 × 3

Example 2:

Input: 8
Output: true
Explanation: 8 = 2 × 2 × 2

Example 3:

Input: 14
Output: false 
Explanation: 14 is not ugly since it includes another prime factor 7.

Note:

1. 1 is typically treated as an ugly number.
2. Input is within the 32-bit signed integer range: [−2³¹,  2³¹ − 1].

3. class Solution(object):
       def isUgly(self, num):
           """
           :type num: int
           :rtype: bool
           """
           # greddy        
           if num <= 0: return False
           for x in [2, 3, 5]:
               while num % x == 0:
                   num = num / x
           return num == 1        
   

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