leetcode6:Zigzag Conversion@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 "PAHNAPLSIIGYIR".

首先明白题意，给出一个字符串，按照之字形（Zigzag）排列成矩形，将矩阵每一行连接起来构成一个字符串。

将矩阵压缩得到：

 #-*-coding:utf-8-*-

 class Solution(object):
     def convert(self, s, numRows):
         """
         :type s: str
         :type numRows: int
         :rtype: str
         """
         if numRows == 1:
             return s
         zigzag = ['' for i in range(numRows)]  # 初始化zigzag为['','','']
         row = 0                                # 当前的行数
         step = 1                               # 步数：控制数据的输入
         for c in s:
             if row == 0:
                 step = 1
             if row == numRows - 1:
                 step = -1
             zigzag[row] += c
             row += step
         return ''.join(zigzag)