robot paths c#

using System;

public class Test
{
    public static void Main()
    {
        Console.WriteLine("Hello");
    }

    public static int count = 0;
    public static int robotPaths(List<List<int>> matrix)
    {
        Helper(matrix, 0, 0);

        return count;
    }

    public static void Helper(List<List<int>> matrix, int i, int j)
    {
        if(matrix[i][j] == 1)
            return;

        if(i == matrix.Count - 1 && j == matrix[i].Count - 1)
        {
            count++;
            return;
        }
        /*
          1   1   1
          0   1   1
          0   0   0
        */
        matrix[i][j] = matrix[i][j] == 0 ? 1 : 0;

        if(i < matrix.Count - 1)
            Helper(matrix, i+1, j);

        if(j < matrix[i].Count - 1)
            Helper(matrix, i, j+1);

        if(i > 0)
            Helper(matrix, i-1, j);

        if(j > 0)
            Helper(matrix, i, j-1);

        matrix[i][j] = matrix[i][j] == 0 ? 1 : 0;
    }
}

/*
public static void Helper(List<List<int>> matrix, int i, int j)
    {
        if(matrix[i][j] == 1)
            return;

        if(i == matrix.Count - 1 && j == matrix[i].Count - 1)
        {
            count++;
            return;
        }

        matrix[i][j] = 1;

        if(i < matrix.Count - 1 && matrix[i+1][j] == 0)
            Helper(matrix, i+1, j);

        if(j < matrix[i].Count - 1 && matrix[i][j+1] == 0)
            Helper(matrix, i, j+1);

        if(i > 0 && matrix[i-1][j] == 0)
            Helper(matrix, i-1, j );

        if(j > 0 && matrix[i][j-1] == 0)
            Helper(matrix, i, j-1);

        matrix[i][j] = 0;
    }
*/