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)