Due: Tuesday, August 15

Please upload your source code files using CSNS. Note that file uploading will be disabled automatically after 11:59PM of the due date, so please turn in your work on time.

[Problem Description] Tic Tac Toe is a game played on a 3 by 3 grid by two players, Player 1 and Player 2. Player 1 starts by placing a circle (which can be represented by the letter O) at an unoccupied grid position. Then Player 2 places a cross (which can be represented by a letter X) at an unoccupied grid position. Play alternates between Player 1 and 2 until one player's symbols occupy an entire line (vertical, horizontal, or diagonal), in which case that player wins; or the grid is filled, in which case the game is tied.

For this assignment you are going to implement the Tic Tac Toe game with a Java GUI application. In particular, your GUI should include at least the following components:

• A panel with nine buttons that are arranged in a 3 by 3 grid, which represents the Tic Tac Toe board. A mouse click at an unoccupied grid position will place the symbol of a player at that position. We assume that the game is played by two human players, and Player 1 always makes the first move.
  
• Two additional buttons, one for starting a new game, and one for exit the game.
• A label which displays the following message as appropriate:
• "Player 1's move:"
• "Player 2's move:"
• "Player 1 won!"
• "Player 2 won!"
• "Game tied!"
  

Note that your GUI interface should automatically adjust to the size of the window. For example, when the window is resized, the board should be enlarged or shrinked accordingly.

[AI Player] For extra credit, add another game mode where a human player can play with an AI player. The AI player follows a simple strategy:

• First check whether it already has two symbols lined up and the third position in the same line unoccupied. If so, make the winning move.
• If there's no winning move, check whether it needs to stop a winning move by the opponent.
• If there's no winning move by either side, make a move at a randomly chosen, unoccupied position.

[Grading] The total points for this project is 100, with 40 extra credit if you choose to implement an AI player.

• GUI (50pt)
  
• Game mechanics (50pt)
  
• AI player (extra credit 40pt)