【打卡贴】（No.006）从零开始刷LeetCode

P   A   H   N
A P L S I I G
Y   I   R

string convert(string s, int numRows);

输入: s = "PAYPALISHIRING", numRows = 3输出: "PAHNAPLSIIGYIR"

输入: s = "PAYPALISHIRING", numRows = 4输出: "PINALSIGYAHRPI"解释:P     I    N
A   L S  I G
Y A   H R
P     I

def convert(self, s, numRows):
    str_length = len(s)
    # 两列之间的差
    node_length = 2 * numRows - 2  
    result = ""
    if str_length == 0 or numRows == 0 
         \ or numRows == 1:
        return s
    # 从第一行遍历到最后一行
    for i in range(numRows): 
        for j in range(i, str_length, node_length):
            # 第一行和最后一行
            还有普通行的整列数字
            result += s[j]  
            if i != 0 and i != numRows - 1 and \
              j - 2 * i + node_length < str_length:
                # 单列行的数字
                result += s[j - 2 * i + node_length]  
    return result