https://leetcode.com/problems/zigzag-conversion/

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 text, int nRows);

convert("PAYPALISHIRING", 3) should return "PAHNAPLSIIGYIR".

 

class Solution {public:    string convert(string s, int numRows) {        if(numRows == 1)return s;        string* a = new string[numRows];        string ans;        int n = 2 * numRows - 2;        for(int i = 0;i < s.size();i++)        {            int r = i % n;            int l = r % numRows;            if(l == r)a[l] += s[i];            else a[numRows - l - 2] += s[i];        }        for(int i = 0;i < numRows;i++){            ans += a[i];        }        return ans;    }};