[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;
    }
};