CS440: Introduction to Artificial Intelligence
Fall 2008
Programming Assignment #1: “Tri-State Othello”
Due Thursday, Oct. 2nd, at noon.
Introduction
Othello is a popular board game from Pressman Toys (a variant on the older game of Go). For
this assignment, you will write a program based on opponent search that plays a variant of
Othello.
Othello is a two-player game. Taking turns, one player places white stones on a grid while the
other player places black stones on the grid. Whichever player has the most stones on the grid at
the end of the game wins. The game ends when every grid square has a stone on it.
The key to Othello is to outflank your opponent. When a stone is placed on a square, it
“outflanks” one or more opponent pieces if they form a contiguous straight line (vertical,
horizontal or diagonal, with no empty spaces) between two stone of the same color. When this
happens, the outflanked pieces change from the opponent’s color to the player’s color. Note that
outflanking is not recursive: one of the flanking pieces must be the newly played piece. Also,
every move must outflank at least one of your opponent’s pieces. If a player cannot play a stone
that outflanks any of the opponent’s stones, then that player’s turn is skipped. It is not legal to
skip a turn, however, if a legal move exists. For the complete rules to Othello (with illustrations),
see the official rules from Pressman Toys. They are accessible through the External Links page
on the class web site.
Tri-state Othello is just like Othello, with the following exceptions: (1) the initial board size
varies, and the board may not be square (although it is always a rectangular grid); and (2) some of
the grid squares are marked ‘E’ (for empty). These squares may not be filled, yet they count as
empty squares for flanking purposes. Each game will begin with on a different size board with a
different pattern of squares marked ‘E’, and continues until all the squares not marked ‘E’ are
full. This is designed to interfere with traditional Othello strategies, and thereby remove any
advantage that previous experience with Othello might bring.
The Challenge
Your assignment is to write a program based on opponent search that selects the next move in a
game of Tri-state Othello. Your program will be given the name of an input file that depicts the
current state of the board, and indicates whether you are playing white or black. Your program
should write a grid coordinate (x,y) to std::cout (in C++) or standard.out (in Java), or the word
“skip” if your player is unable to move.
You may write your program in either C++ or Java (any other language must be explicitly
approved by the instructor). The input file is an ASCII file. The first line begins with one of two
characters -- ‘B’ or ‘W’ – indicating whether your program is playing black or white. This is
followed by white space, the width of the grid, more whitespace, the height of the grid, and a
newline. The rest of the file contains the current state of the board. There are height additional
