[leetcode]6Z字变换

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

class Solution:
    def convert(self, s: str, numRows: int) -> str:
        length=len(s)
        if(numRows==1):
            return s
        num=numRows*2-2
        group=length//num+1
        
        def gets(i:int):
            if i>=length:
                return ""
            else:
                return s[i]
            
        ans=''
        for i in range(numRows):
            for j in range(group):
                head=j*num
                if i==0:
                    ans+=gets(head+i)
                elif i==num//2:
                    ans+=gets(head+i)
                else:
                    ans+=gets(head+i)
                    ans+=gets(head+num-i)
        return ans