using System;

public class Program

{

    public static void Main()

    {

        int[,] matrix = {

        { 1, 1, 1, 1, 1 },

        { 1, 1, 1, 0, 0 },

        { 1, 1, 1, 0, 0 },

        { 1, 1, 1, 0, 0 },

        { 1, 1, 1, 1, 1 } };

​

​

      Console.WriteLine(getSubMatrix(matrix));

    }

      public static int getSubMatrix(int[,] matrix)

    {

          int max = 0;

          int row = matrix.GetLength(0);

          int col = matrix.GetLength(0);

          for(int r=1; r < row; r++)

          {

            for(int c = 1; c < col; c++)

            {

                if(matrix[r, c] == 1)

                {

                    int top = matrix[r-1, c];

                    int left = matrix[r, c-1];

                    int diag = matrix[r-1, c-1];

                    int mini = getMin(top, left, diag);

                    matrix[r, c] += mini;

                    if(max < matrix[r, c]){

                        max = matrix[r, c];

                    }

                }

            }

          }

          return max;

    }

     public static int getMin(int a, int b, int c)

     {

         int min = 0;

         int r = Math.Min(a, b);

         min = Math.Min(r, c);

         return min;         

     }

}

​

​