[LeetCode] 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   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".

 Solution:

class Solution {

public:

    string convert(string s, int nRows) {

        string *tmpS = new string[nRows + 1];

        string ans;

        if(nRows < 2) return s;

        

        bool down = true;

        int row = 0;

        

        for(int i = 0;i < s.length();i++)

        {

            if(row == -1)

            {

                row = 1;

                down = true;

                tmpS[row] += s[i];

                row++;

            }

            else if(row == nRows)

            {

                row = nRows - 2;

                down = false;

                tmpS[row] += s[i];

                row--;

            }

            else

            {

                tmpS[row] += s[i];

                if(down) row++;

                else row--;

            }

        }

        

        for(int i = 0;i < nRows;i++)

            ans += tmpS[i];

        return ans;

    }

};