一道找规律的题，找出各个字母位置之间的规律即可。不过要注意当numRow为1时需要特殊处理

 1 class Solution:
 2     def convert(self, s: str, numRows: int) -> str:
 3         length=len(s)
 4         if(numRows==1):
 5             return s
 6         num=numRows*2-2
 7         group=length//num+1
 8         
 9         def gets(i:int):
10             if i>=length:
11                 return ""
12             else:
13                 return s[i]
14             
15         ans=''
16         for i in range(numRows):
17             for j in range(group):
18                 head=j*num
19                 if i==0:
20                     ans+=gets(head+i)
21                 elif i==num//2:
22                     ans+=gets(head+i)
23                 else:
24                     ans+=gets(head+i)
25                     ans+=gets(head+num-i)
26         return ans
27