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A functional implementation of Tic-Tac-Toe in Scala. Human vs. computer, computer moves are legal, but purely random.
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| /* | |
| * Code contributed to Rosetta Code: <http://rosettacode.org/wiki/Tic-tac-toe#Scala> | |
| * | |
| * Creative commons license "CC0 1.0 Universal (CC0 1.0)" | |
| * <http://creativecommons.org/publicdomain/zero/1.0/> | |
| * To the extent possible under law, Rubén Béjar <http://www.rubenbejar.com> | |
| * has waived all copyright and related or neighboring rights to this | |
| * source file. This work is published from: Spain. | |
| * | |
| * Computers vs. human. Human starts. | |
| * Computer plays 'O' and human plays 'X'. | |
| * Computer moves are legal, but purely random. | |
| */ | |
| package object tictactoe { | |
| val Human = 'X' | |
| val Computer = 'O' | |
| val BaseBoard = ('1' to '9').toList | |
| val WinnerLines = List((0,1,2), (3,4,5), (6,7,8), (0,3,6), (1,4,7), (2,5,8), (0,4,8), (2,4,6)) | |
| val randomGen = new util.Random(System.currentTimeMillis) | |
| } | |
| package tictactoe { | |
| class Board(aBoard : List[Char] = BaseBoard) { | |
| def availableMoves = aBoard.filter(c => c != Human && c != Computer) | |
| def availableMovesIdxs = for ((c,i) <- aBoard.zipWithIndex if c != Human && c != Computer) yield i | |
| def computerPlays = new Board(aBoard.updated(availableMovesIdxs(randomGen.nextInt(availableMovesIdxs.length)), Computer)) | |
| def humanPlays(move : Char) = new Board(aBoard.updated(aBoard.indexOf(move), Human)) | |
| def isDraw = aBoard.forall(c => c == Human || c == Computer) | |
| def isWinner(winner : Char) = | |
| WinnerLines.exists{case (i,j,k) => aBoard(i) == winner && aBoard(j) == winner && aBoard(k) == winner} | |
| def isOver = isWinner(Computer) || isWinner(Human) || isDraw | |
| def print { | |
| aBoard.grouped(3).foreach(row => println(row(0) + " " + row(1) + " " + row(2))) | |
| } | |
| def printOverMessage { | |
| if (isWinner(Human)) println("You win.") | |
| else if (isWinner(Computer)) println("Computer wins.") | |
| else if (isDraw) println("It's a draw.") | |
| else println("Not over yet, or something went wrong.") | |
| } | |
| } | |
| object TicTacToe extends Application { | |
| def play(board : Board, turn : Char) { | |
| // Reads a char from input until it is one of | |
| // the available moves in the current board | |
| def readValidMove() : Char = { | |
| print("Choose a move: ") | |
| val validMoves = board.availableMoves | |
| val move = readChar | |
| if (validMoves.contains(move)) { | |
| move | |
| } else { | |
| println("Invalid move. Choose another one in " + validMoves) | |
| readValidMove() | |
| } | |
| } | |
| board.print | |
| if (board.isOver) { | |
| board.printOverMessage | |
| return | |
| } | |
| if (turn == Human) { // Human plays | |
| val nextBoard = board.humanPlays(readValidMove) | |
| play(nextBoard, Computer) | |
| } else { // Computer plays | |
| println("Computer plays: ") | |
| val nextBoard = board.computerPlays | |
| play(nextBoard, Human) | |
| } | |
| } | |
| play(new Board(),Human) | |
| } | |
| } |
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