HackerRank - Connected Cell in a grid - using DFS, using ref value to track the count.

ConnectedCellInaGrid_May11_p3_usingDFS_usingRef.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace connectedCellsInaGrid_May11_usingDFS_PassingRef
{
    class Program
    {
        static void Main(string[] args)
        {
            int rows = Convert.ToInt32(Console.ReadLine());
            int cols = Convert.ToInt32(Console.ReadLine());

            int[,] arr = new int[rows, cols];

            for (int i = 0; i < rows; i++)
            {
                string[] strA = Console.ReadLine().Split(' ');

                for (int j = 0; j < cols; j++)
                    arr[i, j] = Convert.ToInt32(strA[j]);
            }

            Console.WriteLine(countConnectedCells(arr, rows, cols));
        }

        public static int countConnectedCells(int[,] arr, int rows, int cols)
        {
            int max = Int32.MinValue;

            for (int i = 0; i < rows; i++)
                for (int j = 0; j < cols; j++)
                {
                    int count = 0; 
                    countConnectedCellsUsingDFS(arr, rows, cols, i, j, ref count);
                    max = count > max ? count : max;
                }

            return max;
        }

        private static void countConnectedCellsUsingDFS(int[,] arr, int rows, int cols, int startX, int startY, ref int registerNo)
        {
            if (!inBound(startX, startY, rows, cols) || arr[startX, startY] == 0)
                return ;

            arr[startX, startY] = 0;

            registerNo ++;
            for (int i = -1; i <= 1; i++)
                for (int j = -1; j <= 1; j++)
                {
                    int neighbor_X = startX + i;
                    int neighbor_Y = startY + j;

                    countConnectedCellsUsingDFS(arr, rows, cols, neighbor_X, neighbor_Y, ref registerNo);
                }

            return ;
        }

        private static bool inBound(int x, int y, int rows, int cols)
        {
            return (x >= 0 && x < rows) && (y >= 0 && y < cols);
        }
    }
}