HackerRank - Connected Cell In a Grid - using stack, using DFS

ConnectedCellInaGrid_May11_UsingDFS_stack.cs

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

namespace ConnectedCellInaGrid_May11_usingStack_usingDFS
{
    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(connectedCells(arr, rows, cols)); 
        }

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

            for(int i = 0; i < rows; i++)
                for (int j = 0; j < cols; j++)
                {
                    if (arr[i, j] == 1)
                    {
                        int value = connectedCells_usingDFS_stack(arr, rows, cols, i, j);
                        max = value > max ? value : max;
                    }
                }

            return max; 
        }

        private static int connectedCells_usingDFS_stack(int[,] arr, int rows, int cols, int startX, int startY)
        {
            Stack<int> stack = new Stack<int>();

            arr[startX, startY] = 0;
            stack.Push(calculatedKey(startX, startY));

            int count = 0; 
            while (stack.Count > 0)
            {
                int key = (Int32)stack.Pop();

                int tmpX = key / 10;
                int tmpY = key % 10; 

                for(int i=-1; i<= 1; i++)
                    for (int j = -1; j <= 1; j++)
                    {
                        int neighbor_X = tmpX + i;
                        int neighbor_Y = tmpY + j;

                        if (isInBound(neighbor_X, neighbor_Y, rows, cols) && arr[neighbor_X, neighbor_Y] == 1)
                        {
                            arr[neighbor_X, neighbor_Y] = 0;
                            stack.Push(calculatedKey(neighbor_X, neighbor_Y)); 
                        }
                    }

                count++; 
            }

            return count; 
        }

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

        private static int calculatedKey(int startX, int startY)
        {
            return startX * 10 + startY; 
        }
    }
}