CMSC 15100
Autumn 2009
Introduction to Computer Science Project 2
November 16
Tic-tac-toe
Due: November 23; 10pm
Introduction
Your task in this project is to implement the game tic-tac-toe, including a simple computer player.
The game is played on a 3×3board; the human player goes first and places an “X” on the board,
then the computer places an “O”, and so on, until either one player gets three in a row (a winning
postion) or there are no more moves (a draw).
You will use the Intermediate Student with Lambda language and the world.ss teachpack
for this project. You should follow the steps outlined below and test the code for each step before
moving onto the next step.
Step 1 — data structures
As in Project 1, the playing area (or board) is divided up into square cells. We refer to a cell by
its row and column (hr, ci), with cell h0,0ibeing the upper-left corner of the board and cell h2,2i
being the lower-right corner. The first step is to define the constants and data structures that are used
to represent the state of the game.
;; a board consists of the current player, the opponent, and the
;; state of the game, where the state of the game is either ’X or
;; ’O when there is a winner, ’draw when the game is drawn, or
;; ’none when the game is in progress.
(define-struct board (player opponent winner))
;; a player is a name (’X or ’O) and a sorted list of pieces
(define-struct player (name pieces))
;; a cell is a row and column
(define-struct cell (row col))
Notice that the board representation uses the order of the players to distinguish which player gets
the next move. After each move, the players are swapped.
