TicTaeToe.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace _05TicTaeToe
{
    public partial class TicTaeToe : System.Web.UI.Page
    {
        protected int[,] board; //3x3 is the size of Tic-Tac-Toe's board
        protected int turn;

        protected Dictionary<int[,], int> tictactoe = new Dictionary<int[,], int>();

        protected void Page_Load(object sender, EventArgs e)
        {
            if (ViewState.Count > 0)//if (IsPostBack)
            {
                this.tictactoe = (Dictionary<int[,], int>)ViewState["tictactoe"];
                this.board = this.tictactoe.Keys.First();
                this.turn = this.tictactoe.Values.First();

                if ((this.turn % 2) == 1)
                {
                    ComputerPlay();
                }
            }
            else
            {
                InitializeBoard();
                this.turn = 0;
            }
        }

        private void ComputerPlay()
        {
            Random rnd = new Random();
            int index = rnd.Next(0, 9);
            int[] position = GetRowAndCol(index);
            int row = position[0];
            int col = position[1];

            bool isAvailable = CheckIsAvailable(row, col);
            if (isAvailable)
            {
                FillComputerCell(index);
                this.board[row, col] = 2;
                this.turn++; //make it (turn % 2) == 0 to be a Human's turn
            }
            else
            {
                ComputerPlay();
            }
        }

        private void FillComputerCell(int index)
        {
            string path = "images/2.png";
            switch (index)
            {
                case 0: Imagebutton0.ImageUrl = path;
                    break;
                case 1: Imagebutton1.ImageUrl = path;
                    break;
                case 2: Imagebutton2.ImageUrl = path;
                    break;
                case 3: Imagebutton3.ImageUrl = path;
                    break;
                case 4: Imagebutton4.ImageUrl = path;
                    break;
                case 5: Imagebutton5.ImageUrl = path;
                    break;
                case 6: Imagebutton6.ImageUrl = path;
                    break;
                case 7: Imagebutton7.ImageUrl = path;
                    break;
                case 8: Imagebutton8.ImageUrl = path;
                    break;
                default: throw new BadImageFormatException("Bad image ID!");
            }
        }

        private void InitializeBoard()
        {
            int filler = int.MinValue;
            this.board = new int[3, 3];
            for (int i = 0; i < this.board.GetLength(0); i++)
            {
                for (int j = 0; j < this.board.GetLength(1); j++)
                {
                    this.board[i, j] = filler;
                    filler++;
                }
            }
        }

        protected void Page_PreRender(object sender, EventArgs e)
        {
            if (this.tictactoe.ContainsKey(this.board))
            {
                this.tictactoe[this.board] = this.turn;
            }
            else
            {
                this.tictactoe.Add(this.board, this.turn);
            }
            ViewState["tictactoe"] = this.tictactoe;
        }
        #region ImageButtons_Clicked

        protected void Imagebutton0_click(object sender, EventArgs e)
        {
            Play(0, this.Imagebutton0);
        }

        protected void Imagebutton1_click(object sender, EventArgs e)
        {
            Play(1, this.Imagebutton1);
        }

        protected void Imagebutton2_click(object sender, EventArgs e)
        {
            Play(2, this.Imagebutton2);
        }

        protected void Imagebutton3_click(object sender, EventArgs e)
        {
            Play(3, this.Imagebutton3);
        }

        protected void Imagebutton4_click(object sender, EventArgs e)
        {
            Play(4, this.Imagebutton4);
        }

        protected void Imagebutton5_click(object sender, EventArgs e)
        {
            Play(5, this.Imagebutton5);
        }

        protected void Imagebutton6_click(object sender, EventArgs e)
        {
            Play(6, this.Imagebutton6);
        }

        protected void Imagebutton7_click(object sender, EventArgs e)
        {
            Play(7, this.Imagebutton7);
        }

        protected void Imagebutton8_click(object sender, EventArgs e)
        {
            Play(8, this.Imagebutton8);
        }

        #endregion

        protected void Play(int index, ImageButton clickedImage)
        {
            bool isFinished = false;
            if (this.turn != 0)
            {
                isFinished = CheckForFinish();
            }

            if (!isFinished)
            {
                int[] position = GetRowAndCol(index);
                int row = position[0];
                int col = position[1];

                bool isAvailable = CheckIsAvailable(row, col);
                if (isAvailable)
                {
                    this.board[row, col] = 1;
                    FillCell(clickedImage);
                    this.turn++; //make it (turn % 2) == 1 to be a PC's turn
                }
                else
                {
                    Play(index, clickedImage);
                }
            }
            else
            {
                Response.Write("The game is finished!"); //just an example
            }
        }

        private void FillCell(ImageButton clickedImage)
        {
            clickedImage.ImageUrl = "images/1.png";
        }

        #region Checks For Finishing
        private bool CheckForFinish()
        {
            bool isFinishedByRow = CheckRow();
            bool isFinishedByCol = CheckCol();
            bool isFinishedByDiagonal = CheckDiagonal();
            int counter = 0;
            if (isFinishedByRow)
            {
                counter++;
            }
            if (isFinishedByCol)
            {
                counter++;
            }
            if (isFinishedByDiagonal)
            {
                counter++;
            }

            if (counter == 0)
            {
                return false;
            }
            else
            {
                return true;
            }

        }

        private bool CheckDiagonal()
        {
            if (this.board[0, 0] == this.board[1, 1] && this.board[1, 1] == this.board[2, 2])
            {
                return true;
            }
            if (this.board[0, 2] == this.board[1, 1] && this.board[2, 0] == this.board[1, 1])
            {
                return true;
            }
            else
            {
                return false;
            }
        }

        private bool CheckCol()
        {
            for (int i = 0; i < this.board.GetLength(0); i++)
            {
                bool isFinished = true;
                for (int j = 0; j < this.board.GetLength(1) - 1; j++)
                {
                    if (this.board[j, i] == this.board[j + 1, i])
                    {
                        continue;
                    }
                    else
                    {
                        isFinished = false;
                        break;
                    }
                }
                if (isFinished)
                {
                    return true;
                }
            }
            return false;
        }

        private bool CheckRow()
        {
            for (int i = 0; i < this.board.GetLength(0); i++)
            {
                bool isFinished = true;
                for (int j = 0; j < this.board.GetLength(1) - 1; j++)
                {
                    if (this.board[i, j] == this.board[i, j + 1])
                    {
                        continue;
                    }
                    else
                    {
                        isFinished = false;
                        break;
                    }
                }
                if (isFinished)
                {
                    return true;
                }
            }
            return false;
        }
        #endregion
        private bool CheckIsAvailable(int row, int col)
        {
            if (this.board[row, col] != 1 && this.board[row, col] != 2)
            {
                return true;
            }
            else
            {
                return false;
            }
        }

        private int[] GetRowAndCol(int index)
        {
            int row;
            if (index < 3)
            {
                row = 0;
            }
            if (index >= 3 && index <= 5)
            {
                row = 1;
            }
            else
            {
                row = 2;
            }
            int col = index % 3;

            int[] position = new int[2];
            position[0] = row;
            position[1] = col;
            return position;
        }
    }
}