【LeetCode with Python】 6. ZigZag Conversion

题目

原题页面:https://leetcode.com/problems/zigzag-conversion/
本文地址:http://leetcode.xnerv.wang/zigzag-conversion/
题目类型:String
难度评价:Easy

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

下标计算处理,控制好循环条件,下标不要越界即可。


代码

class Solution:
    # @return a string
    def convert(self, s, nRows):
        if 1 == nRows:
            return s

        len_s = len(s)
        piece_len = 2 * (nRows - 1)

        result = ""
        index = 0
        while index < len_s:
            result += s[index]
            index += piece_len
        for m in range(1, nRows - 1):
            index = m
            while index < len_s:
                result += s[index]
                right_index = index + (nRows - m - 1) * 2
                if right_index < len_s:
                    result += s[right_index]
                index += piece_len
        index = nRows - 1
        while index < len_s:
            result += s[index]
            index += piece_len

        return result

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