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   NA P L S I I GY   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 = 3Output: "PAHNAPLSIIGYIR"

Example 2:

Input: s = "PAYPALISHIRING", numRows = 4Output: "PINALSIGYAHRPI"Explanation:P     I    NA   L S  I GY A   H RP     I

代码：

class Solution {public:    string convert(string s, int nRows) {        if (nRows <= 1) return s;        string res = "";        int size = 2 * nRows - 2;        for (int i = 0; i < nRows; ++i) {            for (int j = i; j < s.size(); j += size) {                res += s[j];                int tmp = j + size - 2 * i;                if (i != 0 && i != nRows - 1 && tmp < s.size()) res += s[tmp];            }        }        return res;    }};

　　找规律找到每个字符在新的字符串中的位置