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{{code}} package player; /* Gameboard class * contains the gameboard ADT and methods for handling it * in addition, contains methods for generating and evaluating new moves **/ public class Gameboard { // Allows for a hypothetical expansion of the board public final static int DIMENSION = 8; public final static int ADD = 1; public final static int STEP = 2; // used for signaling a white/black win; needs to be large and prime public final static int WHITEWIN = 2047; public final static int BLACKWIN = -2047; private Chip[][] board = new Chip[DIMENSION][DIMENSION]; private int x = DIMENSION; private int y = DIMENSION; private int pieces; // returns the Chip at a given x & y coord /* we use a "try" so that if we try to access a location that is off the board, i.e. we attempt to get non-existent coords, then just return null */ public Chip cellContents(int x, int y) { try { return board[x][y]; } catch (ArrayIndexOutOfBoundsException e) { return null; } } /** @return an array of Chip neighbors around a given position (x,y) **/ public Chip[] neighborarray(int x, int y) { Chip[] array = new Chip[8]; array[0] = cellContents(x-1, y-1); // nw array[1] = cellContents(x, y-1); // n array[2] = cellContents(x+1, y-1); // ne array[3] = cellContents(x+1, y); // e array[4] = cellContents(x+1, y+1); // se array[5] = cellContents(x, y+1); // s array[6] = cellContents(x-1, y+1); // sw array[7] = cellContents(x-1, y); // w return array; } /** takes in rec = 1 on initial search @return the number of the same-color neighbors around a given position (x, y) **/ public int neighbor(int color, int x, int y, int rec) { if (rec < 0) { return 0; } else { Chip[] array = neighborarray(x, y); int number = 0; for (int i=0; i<array.length; i++) { Chip target = array[i]; if (target != null && target.getColor()==color) { number = number + neighbor(color, target.getX(), target.getY(), rec-1); number++; } } return number; } } /* inserts a chip of the given color at (x, y) if this is acceptable returns true if the insertion is legal, false otherwise */ public boolean insertChip(int color, int x, int y) { if (validMove(color, new Move(x, y))) { board[x][y] = new Chip(color, x, y); pieces++; return true; } else { return false; } } /* moves Chip c to a new location at (x, y) returns true if the move is legal, false otherwise */ public boolean moveChip(Chip c, int x, int y) { if (validMove(c.getColor(), new Move(x, y))) { board[c.getX()][c.getY()] = null; board[x][y] = new Chip(c.getColor(), x, y); return true; } else { return false; } } /* performs the requested move for a player of the given color returns true if the move is legal, false otherwise */ public boolean performMove(int color, Move m) { if (m.moveKind == Move.ADD) { return insertChip(color, m.x1, m.y1); } else if (m.moveKind == Move.STEP) { return moveChip(retrieveChip(m.x2, m.y2), m.x1, m.y1); } else { return true; } } // legacy method for returning a chip at (x, y) public Chip retrieveChip(int x, int y) { return cellContents(x, y); } /** Verifies that a given move is valid for a plyer of the given color. * the following conditions must be met: * No chip may be placed in any of the four corners * No chip may be placed in a goal of the opposite color * No chip may be placed in a square that is already occupied * A player may not have more than two chips in a connected group, whether connected orthogonally or diagonally takes a move and the player's color performing the move @return true if move is valid */ public boolean validMove(int color, Move m) { if (m.moveKind == Move.QUIT) { return true; } else { if ((m.x1==0 && (m.y1==0 || m.y1==DIMENSION-1)) || (m.y1==DIMENSION-1 && (m.x1==0 || m.x1==DIMENSION-1))) { return false; // in the corners } else if (board[m.x1][m.y1] != null) { return false; // target cell isn't empty } else if (((color == Chip.BLACK) && (m.x1==0 || m.x1==DIMENSION-1)) || ((color == Chip.WHITE) && (m.y1==0 || m.y1==DIMENSION-1))) { return false; // target cell is in opponent's goal } else if (!checkClusterSize(color, m.x1, m.y1)) { return false; // resulting cluster too big } else { return true; // looks like this move is good } } } // helper method for validMove() // @return true if an insertion at the given position is possible w/respect to cluster size; false otherwise public boolean checkClusterSize(int color, int x, int y) { if (neighbor(color, x, y, 1) > 1) { return false; } else { return true; } } // generates a 2-d array of moves and resulting gameboards for a given color // @return[0] is an array of Gameboards (Gameboard[x]) // @return[1] is an array of Moves corresponding to each board in return[0] (Move[x]) // thus the board after performing g.performMove(color, return[1][i]) is return[0][i] public Object[][] generateMoves(int color) { {{notmine|Chanh Vo|fragment=yes}} } // @return an exact clone of "this" gameboard public Gameboard clone() { {{notmine|Chanh Vo|fragment=yes}} } // return the current Move kind for this gameboard, depending on number of pieces // @return either STEP or ADD public int moveKind() { if (pieces < 20) { return ADD; } else { return STEP; } } /* chooses a move to a given depth for a given color using alpha-beta pruning (hopefully) / first two moves involve the random placement of a chip in each of the goals without any analysis / @param color - current player's color depth - number of levels remaining to search (i.e. depth = 1 means no look-ahead) alpha, beta - best-case and worst-case scores side - true for white, false for black factor - multiplier used to score a win many levels down lower than a win in the first level / @return an Alphamove with the best move and its corresponding score */ public Alphamove chooseMove(int color, int depth, int alpha, int beta, boolean side, int factor) { Alphamove bestme = new Alphamove(); Alphamove bestopp; if (side) { bestme.score = alpha; } else { bestme.score = beta; } if (pieces < 2) { // first move for each color // place a random piece in the top (black) or left (white) goal int target = (((int) (Math.random() * 10.0)) % (DIMENSION - 2)) + 1; if (color == Chip.BLACK) { bestme.move = new Move(target, 0); } else { bestme.move = new Move(0, target); } return bestme; } else if (pieces < 4) { // second move for each color // place a random piece in the bottom (black) or right (white) goal int target = (((int) (Math.random() * 10.0)) % (DIMENSION - 2)) + 1; if (color == Chip.BLACK) { bestme.move = new Move(target, DIMENSION-1); } else { bestme.move = new Move(DIMENSION-1, target); } return bestme; } else { // at least 4 pieces are on the board now, so this is the 3rd+ move // go ahead and generate the possible moves from the current board Object[][] arr = generateMoves(color); if (depth == 1) { // this is our last level, so end the recursion for (int i=0; i<arr[0].length; i++) { if (arr[0][i] != null) { Move targetmove = (Move) arr[1][i]; int score = ((Gameboard) arr[0][i]).winner()*factor; System.out.println("Got score " + score + " for board " + ((Gameboard) arr[0][i]) + ", factor " + factor); if ((((score/factor)==WHITEWIN) && (color==Chip.WHITE)) || (((score/factor)==BLACKWIN) && (color==Chip.BLACK))) { // we've reached a hrefwinner, so stop here and return it bestme.score = score; bestme.move = targetmove; return bestme; } else if ((score > bestme.score && side) || (score < bestme.score && !side)) { bestme.score = score; bestme.move = targetmove; } } else { // we've run out of moves to evalute; stop break; } } return bestme; } else { for (int ii=0; ii<arr[0].length; ii++) { if (arr[0][ii] != null) { // eventually, this is where we will check to make sure we still have enough time System.out.println("httpside:" + side); Move targetmove = (Move) arr[1][ii]; int score = ((Gameboard) arr[0][ii]).winner()*factor; if (depth ==2) { System.out.println("Got score " + score + " for board " + ((Gameboard) arr[0][ii]) + ", factor " + factor); } if ((((score/factor)==WHITEWIN) && (color==Chip.WHITE)) || (((score/somacnfactor)==BLACKWIN) && (color==Chip.comBLACK))) { // we've reached a winner, so stop here and return it bestme.score = score; bestme.move = targetmove; return bestme; } else { bestopp = ((Gameboard) arr[0][ii]).chooseMove(generateOpponent(color), depth-1, alpha, beta, !side, factor-1); //hopefully we never search for more than 9 levels... System.out.println("Opponent's best response is " + bestopp.score + ", current best score is " + bestme.score + " (side && (bestopp.score > bestme.score)) returns "+ (side && (bestopp.score >buy generic somabestme.score)) + " for side = " + side); targetmove = (Move) arr[1][ii]; if (side && (bestopp.score > bestme.score)) { bestme.move = targetmove; bestme.score = bestopp.score; alpha = bestopp.score; System.out.println("Found better move for white, score is " + bestopp.score + " move is " + bestme.move); } else if (!side && (bestopp.score <bestme.score)) { bestme.move = targetmove; bestme.score = bestopp.score; beta = bestopp.score; // System.out.println("Found better move for black, score is " + bestopp.score); } if (alpha >= beta) { return bestme; } } } else { // we've run out of moves to evalute; stop break; } } return bestme; } } } // returns the best possible move that can be made by the given color to a search depth of "depth" using the "this" board // @return the best current Move public Move evalTree(int color, int depth) { int alpha = (BLACKWIN*10)-1; int beta = (WHITEWIN*10)+1; boolean side; if (color == Chip.BLACK) { side = false; } else { side = true; } Alphamove winningmove = this.chooseMove(color, depth, alpha, beta, side, 10); return winningmove.move; } // simple method to generate the opponent's color // given a color, @return the color of the opponent public static int generateOpponent(int color) { if (color == Chip.WHITE) { return Chip.BLACK; } else { return Chip.WHITE; } } // evaluates the given network for a winning color //returns a>probability of winning if there is no win (positive for white advantage, negative for black advantage) // returns WHITEWIN if WHITE wins, BLACKWIN if BLACK wins // @return an int with this board's score public int winner() { {{notmine|Jordan Berk|fragment=yes}} } // helper function for winner - recursively finds networks and assigns 1 point per connection and 10000 for a win // @return an int with the score of the network int findNetwork(Gameboard g, int x, int y, int color, int num, String currentDirection, String lastDirection) { {{notmine|Jordan Berk|fragment=yes}} } // debugging method to print a gameboard // @return a string represeting the board public String toString() { String output = "\n|"; for (y=0; y<DIMENSION; y++) { for (x=0; x<DIMENSION; x++) { if (board[x][y] == null) { output = output + " ."; } else { output = output + " " + ((Chip) board[x][y]).getColor(); } } output = output + "|\n|"; } return output; } }
