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题目：
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".
链接：https://leetcode.com/problems/zigzag-conversion/
一刷
python
先算s里有多少波峰，然后两轮循环，外循环为numRows，内循环为波峰数量，每一步均计算左右两侧分别是否valid，每个group波谷的范围为左开右闭。
算法边界条件太多，runtime只beat不到10%
class Solution(object): def convert(self, s, numRows): """ :type s: str :type numRows: int :rtype: str """ if len(s) <= numRows or numRows == 1: return s num_group = (len(s) + numRows - 1 ) // (2 * (numRows - 1)) + 1 zigzag_chars = [] for row in range(numRows): for i in range(num_group): left_index = 2 * (numRows - 1) * i - row right_index = 2 * (numRows - 1) * i + row if left_index >= 0 and left_index < len(s): if left_index % (2 * (numRows - 1)) != 0 and left_index % (numRows - 1) == 0: pass else: zigzag_chars.append(s[left_index]) if left_index != right_index and right_index < len(s): zigzag_chars.append(s[right_index]) return ‘‘.join(zigzag_chars)
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原文地址：http://www.cnblogs.com/panini/p/5544573.html
