Leetcode解题-Zigzag Conversion

描述

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”.

分析

这道题要找规律，太烦了，直接参考这里。

代码

Python

class Solution(object):
    def convert(self, s, numRows):
        """        :type s: str        :type numRows: int        :rtype: str        """
        :type s: str
        :type numRows: int
        :rtype: str
        """
        n = len(s)
        if n <= 1 or numRows == 1:
            return s
        rs = []
        gap = 2 * numRows - 2
        for i in xrange(numRows):
            for j, index in enumerate(xrange(i, n, gap)):
                # index = gap * j + i
                rs.append(s[index])
                # not first row either last row
                if i > 0 and i < numRows - 1:
                    k = index + gap - 2 * i
                    if k < n:
                        rs.append(s[k])
        return ''.join(rs)