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 s, int numRows);
Example 1:

Input: s = "PAYPALISHIRING", numRows = 3
Output: "PAHNAPLSIIGYIR"
Example 2:

Input: s = "PAYPALISHIRING", numRows = 4
Output: "PINALSIGYAHRPI"
Explanation:

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

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/zigzag-conversion
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题解讲的真好

class Solution {
public:
    string convert(string s, int numRows) {
        string ret;
        int n = s.size();
        int times = 2*numRows-2;
        if(n<=1) return s;
        if(numRows == 1)return s;
        int i = 0;
        while(times*i<n)
        {
            ret += s[times*i];
            i++;
        }
        for(int j = 1; j<numRows-1; j++)
        {
            ret += s[j];
            for(int i = 1; ;i++)
            {
                if(times*i-j<n) ret += s[times*i-j];
                if(times*i+j<n) ret += s[times*i+j]; 
                else break;
            }
        }
        i = 0;
        while((times*i + numRows-1)<n)
            ret += s[times*i++ + numRows-1];
        return ret;
    } 
};

我画了一个特别丑的图就出来了

Z型排序可以由第一种演变过去。。。Z型还可以变成后面那种，就可以按照代码的思路去写了。。