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 nRows) {        if (nRows == 1 || nRows >= s.size())         {            return s;        }                string str;        int edge = nRows - 1;        for (int i = 0; i < nRows; ++i)         {            int k = i;            while (k < s.size())             {                str += s[k];                if (i == 0 || i == edge)                 {                    k += 2 * edge;                }                else                {                    k += 2 * (edge - k % (edge));                }            }        }        return str;    }};