Leetcode题库——6.Z字形变换

---

@author: ZZQ
@software: PyCharm
@file: convert.py
@time: 2018/9/20 20:12
要求： Z字形变换
将字符串 "PAYPALISHIRING" 以Z字形排列成给定的行数：
P A H N
A P L S I I G
Y I R
之后从左往右，逐行读取字符："PAHNAPLSIIGYIR"
实现一个将字符串进行指定行数变换的函数:

string convert(string s, int numRows);
e.g.:
        输入: s = "PAYPALISHIRING", numRows = 3
        输出: "PAHNAPLSIIGYIR"
        输入：s = "PAYPALISHIRING", numRows = 4
        输出："PINALSIGYAHRPI"

思路： 建一个有numRows个字符串的列表，一个循环写两次列表，一次顺着写，一次反着写，注意下标变化。

class Solution():
    def __init__(self):
        pass

    def convert(self, s, numRows):
        """
        :type s: str
        :type numRows: int
        :rtype: str
        """
        if numRows == 1:
            return s
        s_len = len(s)
        zlist = []
        for i in range(numRows):
            sub_list = ""
            zlist.append(sub_list)
        k = 0
        time = 0
        while k < s_len:
            if time == 0:
                list_index = 0
                while list_index < numRows:
                    if k < s_len:
                        zlist[list_index] += s[k]
                    else:
                        break
                    k += 1
                    list_index += 1
                time += 1
            else:
                list_index = 1
                while list_index < numRows:
                    if k < s_len:
                        zlist[list_index] += s[k]
                    else:
                        break
                    k += 1
                    list_index += 1

            list_index -= 1
            while list_index > 0:
                list_index -= 1
                if k < s_len:
                    zlist[list_index] += s[k]
                else:
                    break
                k += 1
            time += 1
        z_str = ""
        for sub_str in zlist:
            z_str += sub_str
        return z_str


if __name__ == "__main__":
    answer = Solution()
    print answer.convert(s="ABJHFSDKAGFSLABVSJDK", numRows=2)