Leetcode 130 - surrounded region - C# practice, pass online judge

Leetcode130-surroundedRegion.cs

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

namespace Leetcode130_surroundedRegion
{
    /// <summary>
    /// Leetcode 130 surrounded region
    /// https://discuss.leetcode.com/topic/17224/a-really-simple-and-readable-c-solution-only-cost-12ms
    /// First, check the four border of the matrix. If there is a element is
    /// 'O', alter it and all its neighbor 'O' elements to '1'.
    /// Then ,alter all the 'O' to 'X'
    /// At last,alter all the '1' to 'O'
    /*
    For example:

         X X X X           X X X X             X X X X
         X X O X  ->       X X O X    ->       X X X X
         X O X X           X 1 X X             X O X X
         X O X X           X 1 X X             X O X X
    */
    /// </summary>    
    class Program
    {
        static void Main(string[] args)
        {
        }

        /// <summary>
        /// code review on July 14, 2017
        /// </summary>
        /// <param name="board"></param>
        void solve(char[,] board)
        {
            int row, col;

            int rows = board.GetLength(0);
            if (rows == 0)
            {
                return;
            }

            int columns = board.GetLength(1);

            for (row = 0; row < rows; row++)
            {
                check(board, row, 0, rows, columns); // first column

                if (columns > 1) // if more than one column
                {
                    check(board, row, columns - 1, rows, columns); // last column 
                }
            }

            for (col = 1; col + 1 < columns; col++)
            {
                check(board, 0, col, rows, columns); // first row 

                if (rows > 1) // if more than one row
                {
                    check(board, rows - 1, col, rows, columns); // last row
                }
            }

            for (row = 0; row < rows; row++)
            {
                for (col = 0; col < columns; col++)
                {
                    var visit = board[row, col];
                    board[row, col] = visit == '1' ? 'O' : 'X';
                }
            }
        }

        /// <summary>
        /// code review on July 14, 2017
        /// depth first search to mark '0' to '1', 
        /// temporary state of '1', visited status
        /// </summary>
        /// <param name="board"></param>
        /// <param name="row"></param>
        /// <param name="column"></param>
        /// <param name="rows"></param>
        /// <param name="cols"></param>

        void check(char[,] board, int row, int column, int rows, int cols)
        {
            if (board[row, column] == 'O')
            {
                board[row, column] = '1';

                if (row > 1)
                {
                    check(board, row - 1, column, rows, cols);
                }

                if (column > 1)
                {
                    check(board, row, column - 1, rows, cols);
                }

                if (row + 1 < rows)
                {
                    check(board, row + 1, column, rows, cols);
                }

                if (column + 1 < cols)
                {
                    check(board, row, column + 1, rows, cols);
                }
            }
        }
    }
}