public String backtrack(int row, int col, String pathSoFar)
    {
        // TODO: write the recursive backtrack algorithm.
        // fix the return value!
        String out = null;
        int steps = 0;
        markers[row][col] = true;

        if (row == 0 && col == 0
            || row == 0 && col == SIDE_LENGTH
            || row == SIDE_LENGTH && col == 0
            || row == SIDE_LENGTH && col == SIDE_LENGTH)
        {
            return "Found Solution:" + pathSoFar;
        }
        else
        {
            steps = map[row][col];
            if (validateMove(row + steps, col)
                && validateMove(row - steps, col)
                && validateMove(row, col - steps)
                && validateMove(row, col + steps))
            {
                out = move(steps, row, col, pathSoFar);
            }
        }

        return out;
    }

    /**
     * Move.
     *      Runs the moves as
     * @param steps int
     * @param row int
     * @param col int
     * @param pathSoFar string
     * @return String
     */
    public String move(int steps, int row, int col, String pathSoFar)
    {
        String out = "";

        if (markers[row - steps][col] != true)
        {
            out = backtrack(row - steps, col, pathSoFar + "up");
            if (out != null)
            {
                return out;
            }
        }
        else if (markers[row + steps][col] != true)
        {
            out = backtrack(row + steps, col, pathSoFar + "down");
            if (out != null)
            {
                return out;
            }
        }
        else if (markers[row][col - steps] != true)
        {
            out = backtrack(row, col + steps, pathSoFar + "right");
            if (out != null)
            {
                return out;
            }
        }
        else if (markers[row][col + steps] != true)
        {
            out = backtrack(row, col - steps, pathSoFar + "left");
            if (out != null)
            {
                return out;
            }
        }
        return out;
    }

    /**
     * Validate move.
     *      Makes sure the move is valid.
     * @param row int.
     * @param col int
     * @return Boolean.
     */
    public Boolean validateMove(int row, int col)
    {
        boolean out = true;
        if (row < SIDE_LENGTH && col < SIDE_LENGTH)
        {
            out = false;
        }

        return out;
    }