6. ZigZag Conversion Leetcode Python

The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility)

P   A   H   N

A P L S I I G

Y   I   R

And then read line by line: "PAHNAPLSIIGYIR"

Write the code that will take a string and make this conversion given a number of rows:

string convert(string text, int nRows);
convert("PAYPALISHIRING", 3) should return "PAHNAPL

SIIGYIR".

这题的主要特点是要观察出新序列的位置为 2*nRows-2

代码如下

class Solution:
# @return a string
def convert(self, s, nRows):
if nRows==1:
return s
if len(s)<=1:
return s
n=nRows
size=2*n-2
result=[]
for i in range(n):
j=i
while j<len(s):
result.append(s[j])
if i!=0 and i!=n-1 and j+size-2*i<len(s):
result.append(s[j+size-2*i])
j+=size
return "".join(result)