【leetcode】ZigZag Conversion

题目简述

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 "PAHNAPLSIIGYIR".

解题思路：

这个题目有两种做法：第一种是模拟，也就是说我们可以有几行就开几个数组都存起来，最后合到一起就可以了；另一种方法是找规律。因为第一种比较直观，故代码实现了第一种思路：

class Solution:# @return a stringdef convert(self, s, nRows):if nRows == 1:return sgap = nRows - 2res = []for i in range(nRows):res.append([])i = 0while i < len(s):for j in range(nRows):if i >= len(s):breakres[j] += s[i]i += 1for j in range(gap,0,-1):if i >= len(s):breakres[j] += s[i]i += 1ress = ""for i in res:for j in i:ress += jreturn ress