Final Project: Reversi

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1 Final Project: Reversi Reversi is a classic 2-player game played on an 8 by 8 grid of squares. Players take turns placing pieces of their color on the board so that they sandwich and change the color of their opponent s pieces. The games is over when neither player can make a move, and whoever has more pieces at the end of the game is the winner. If you ve never played Reversi, it s easy to find programs on the web to play against. For instance, if you sign up (for free!) at Yahoo! Games 1, you can play Reversi against people around the world. Plus, there s information about the rules and good playing strategies. 2 Reversi Rules At the end of this project is a sample Reversi game. Board 1 shows the initial configuration. Black always moves first. On your turn, you must sandwich at least one opposing piece. Sandwiching is simple, but a bit tricky to explain in words. Here s an example: X A black piece placed at position X will sandwich the three white pieces, and change their color to black, leaving a line of 5 black pieces. In the next example, no sandwiching is possible: X Placing a black piece at position X will not sandwich the white pieces, because the line of white pieces ends with a blank square on the right, not a black piece. Boards1 to 4 below show the start of a sample game. A piece can sandwich any number of opposing pieces, along any column, row, or diagonal. It s not unusual for one move to flip pieces along multiple lines. If on your turn you can t sandwich at least one piece, your turn is over (i.e. you don t put a piece on the board) and your opponent gets to move. If your opponent can t make a move, then the game is over. You must make a move if possible --- you cannot forfeit your turn. Once a piece is placed, it never moves to another square. However, its color might flip many times during the game. The game ends when neither player can make a move. It s possible for the game to end before all 64 squares have been filled. The player with the most pieces on the board at the end of the game is the winner. Ties are possible Be careful: it s easy to end up wasting time playing games here!

2 Required Features Your program should have the following features: The user should do no typing. All user input must come from the mouse. The board must be drawn graphically, allowing the user to place a piece by clicking on a square. You can draw the pieces as X s and O s, for example. Use the Button class from assignment 4 to help you draw the board. When it s the user s turn to make a move, you can (but need not) draw a small tickmark (or other symbol) in all squares where they are allowed to move. If the user clicks on a square with a tick-mark, then a piece is placed there. If they click on any other square, then nothing should happen, because that click corresponds to an impossible or illegal move. The user can choose to play either the black or white pieces. Remember, black always moves first. The user always plays against the computer. Make the computer opponent play as intelligently as possible. One simple strategy is to assign each square of the board a weight, the higher the weight the more valuable the score. When it s the computer s turn to move, it first calculates all legal places it can move to, and then chooses the move with the highest weight. You will have to decide how to assign weights to the squares, of course. Hint: the corner squares are usually the most valuable, so give them a very high weight. The squares surrounding can be given low weights, because typically if you place a piece in a square next to a corner, your opponent can capture the corner on their next move. This strategy does not always work perfectly, but it is probably better than randomly choosing a legal move. 3 During the game, the number of white and black pieces on the board should be displayed on the screen at all times. The user should be able to save the position of the board to disk at any time during a game, and then, at a later time, re-load that position to continue playing. Do not ask the user to type the name of file --- all input is from the mouse. The user should just be able to click an on-screen button and have the game saved or re-loaded automatically. Only one game need be saved. Non-Required Features When developing software, there is always a great temptation to add neat new features. You can probably think of many extra features to add to your Reversi game, e.g. move undo hints (i.e. let the computer suggest a good move) human vs. human and computer vs. computer options different computer skill levels 3 It s possible, although difficult, to get the computer to play well enough to beat any human player. If you are curious about how this might possible, check the web or library for information about minimax search and alpha-beta pruning.

3 saving multiple games on-line tutorial or help explaining the rules of the game to the user But keep this in mind: you won t get marks for any extra features, and you will definitely lose marks if you don t have all the required features. Therefore: don t add any other extra feature until you ve implemented all of the above required features! Implementation Constraints Your game must be implemented in C++ using the textbook s graphics library. 4 You must use at least three classes: A Board class, that contains all the code for the Reversi board. A Human_player class, that contains all the code for a human player. A Computer_player class, that contains all the code the computer player. The exact details of the implementation of these classes are up to you, but please use these names to make it easier for the markers to read your code. You can write other classes if you want. As always, we expect you to use good object-oriented design, and to follow the style rules in the textbook. The Board, Human_player, and Computer_player classes should each be separately compiled modules. Each module must have its own header file and implementation file. For instance, the Board class definition should be stored in the file Board.h, and the implementation should be stored in Board.cpp. The file names should be the same as the class name. Board must be represented using a vector of vector s. For instance, you can represent a matrix of ints like this: vector<vector<int> > board_; // private vble in Board class for(int i = 0; i < 8; ++i) { board_.push_back(vector<int>(8)); // add a row of 8 squares } //for The square-bracket notation can now be used to access individual squares on the board: for(int i = 0; i < 8; ++i) { // initialize all board locations for(int j = 0; j < 8; ++j) { // to 0 board_[i][j] = 0; } // for } //for 4 Do not modify the code in that library in any way. If you do, we will count that as not using the textbook s library.

4 While you must use a vector of vectors, it doesn t necessarily need to be of type vector<vector<int> >. Depending upon your design, you might represent a square with a special Square class, say; then board_ would be of type vector<vector<square> >. It s up to you to decide what s best, although in general you should always do the simplest thing that makes sense. Groups This project should be done in groups of two or three. A two-member team is ideal. Groups cannot have more than three members: this limit is strict, and no exceptions will be made. Part of doing a group project is getting the experience of working with another programmer, so while you can do the project on your own, single-member teams will get a 5% penalty. Also, all projects will be marked with the same marking scheme, and all group members will receive the same mark for the project. You can advertise for a partner on Caucus. What to Hand In Hand in all the source code for your project, and all the usual pages required by the handin guide. Each team should hand in one project, even if you have team members in different sections. Put the name and address of each team member on your cover page. Hands in the following 9 screen shots: 1 showing the initial configuration of your game 2 showing two moves made right after this initial configuration 2 showing the middle of a game (there should be 30 or 40 pieces on the board for these two shots) 2 showing the very last, and the second to last moves of the game 1 showing what happens when you save a game 1 showing what happens when you re-load a game Also, hand in a screen shot of the window showing all the files in your project file (or hand in a print out of your makefile).

5 Sample Game Board 1 Board 2 This is the starting configuration. Black always moves first, and the Xs show black s legal moves. Black must always sandwich one or more white pieces. In general, if a player can t sandwich at least one, they lose their turn and the other player makes a move. The game is over when neither player can make move. Board 3 Black decides to place a piece on the upper-most X. That sandwiches one white piece (the shaded one), which then gets changed to black. Reversi pieces are white on one side, and black on the other, so we say color has flipped. Board 4 After the piece is flipped, the board looks like this. Black has four pieces, and white has one. The Xs show the legal places white can place a piece. White has moved to the lower left X, and after flipping the sandwiched white piece. The Xs show black s legal moves. The game continues in the same fashion.