33.丑数

 1 # -*- coding:utf-8 -*-
 2 class Solution:
 3     def GetUglyNumber_Solution(self, index):
 4         # write code here
 5         if index == 0:
 6             return 0
 7         twopointer = 0
 8         threepointer = 0
 9         fivepointer = 0
10         res = [1]
11         count = 1
12         while count !=index:
13             num = min(res[twopointer]*2,res[threepointer]*3,res[fivepointer]*5)
14             res.append(num)
15             count += 1
16             if num == res[twopointer]*2:#这里三个if一定要是独立的if,不能是elif,因为会有相同的数，当都得到的结果相同时，指针都向后移动,这样就不会有重复的数了
17                 twopointer+=1
18             if num == res[threepointer]*3:
19                 threepointer+=1
20             if num == res[fivepointer]*5:
21                 fivepointer+=1
22         return res[count-1]