leetcode6:Zigzag [email protected]

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：

 1 #-*-coding:utf-8-*-
 2
 3 class Solution(object):
 4     def convert(self, s, numRows):
 5         """
 6         :type s: str
 7         :type numRows: int
 8         :rtype: str
 9         """
10         if numRows == 1:
11             return s
12         zigzag = [‘‘ for i in range(numRows)]  # 初始化zigzag为[‘‘,‘‘,‘‘]
13         row = 0                                # 当前的列数
14         step = 1                               # 步数：控制数据的输入
15         for c in s:
16             if row == 0:
17                 step = 1
18             if row == numRows - 1:
19                 step = -1
20             zigzag[row] += c
21             row += step
22         return ‘‘.join(zigzag)