@Override
public void chooseMove() {
long startTime = System.nanoTime();
Move bestMove = null;
double bestScore = 0;
// We need to initialize alpha and beta -infinity and + infinity respectively.
double alpha = Double.NEGATIVE_INFINITY;
double beta = Double.POSITIVE_INFINITY;
int maxDepth;
for (maxDepth = 1; (System.nanoTime() - startTime) <= maxTime; maxDepth++) {
List<Move> legalMoves = GameState2P.getLegalMoves(state, index);
bestScore = 0;
for (Move m : legalMoves) {
// If we run out time we break out.
if ((System.nanoTime() - startTime) >= maxTime) {
break;
}
GameState2P next = m.doMove(state);
double score = getMinScoreAlphaBeta(next, maxDepth, alpha, beta);
if (bestMove == null || score >= bestScore) {
bestMove = m;
bestScore = score;
}
}
}
System.out.println("Depth: " + maxDepth + " trans score: " + bestScore);
GameState2P newState = bestMove.doMove(state);
game.doMove(index, newState);
}
/*
* Consider all possible moves by our opponent
*/
private double getMinScoreAlphaBeta(
final GameState2P state, int depth, double alpha, double beta) {
double res = Double.POSITIVE_INFINITY;
double score;
// We try to get the current opponent state from the transposition table.
TranspositionEntry entry = minTable.getEntryFromGameState(state);
// Get the opponent's moves.
final List<Move> opponentMoves = GameState2P.getLegalMoves(state, indexOpponent);
// Check if current opp state existed before in table and that the depth is less than the depth
// stored in the entry. We need to check the states as well, as it is possible that two state
// has the same hashcode.
// Then return the previous best minimax score for this state.
if (null != entry && state.equals(entry.getGameState2P()) && depth <= entry.getDepth()) {
res = entry.getMinimax();
}
if (depth == 0 || state.isGameOver()) {
res = state.evaluateState(index);
} else {
Comparator<Move> comparator =
new Comparator<Move>() {
@Override
public int compare(Move move1, Move move2) {
// Check if the current opponent moves exist in the transposition table. If it doesn't
// set minimax
// to positive infinity, in order words the worst result for the opponent.
int lhs =
(null != minTable.getEntryFromGameState(move1.doMove(state)))
? (int) minTable.getEntryFromGameState(move1.doMove(state)).getMinimax()
: (int) Double.POSITIVE_INFINITY;
int rhs =
(null != minTable.getEntryFromGameState(move2.doMove(state)))
? (int) minTable.getEntryFromGameState(move2.doMove(state)).getMinimax()
: (int) Double.POSITIVE_INFINITY;
// If right is lower swap.
if (lhs > rhs) {
return 1;
} else if (lhs == rhs) {
return 0;
} else {
return -1;
}
}
};
// For the minimax score we need to sort the opponent's moves by their scores lowest first, in
// order to optimise
// the search.
Collections.sort(opponentMoves, comparator);
// The opponent will go through their moves and try to get the best minimax score for them.
// Once a promising child move is found store it with the minimax value in the transposition
// table.
for (Move move : opponentMoves) {
GameState2P next = move.doMove(state);
score = getMaxScoreAlphaBeta(next, depth - 1, alpha, beta);
res = Math.min(res, score);
beta = Math.min(beta, score);
if (beta <= alpha) {
//
minTable.addEntry(next, res, depth);
break;
}
}
}
return res;
}
@Override
public void doMove(
String s,
Table table,
WhitePlayer whitePlayer,
BlackPlayer blackPlayer,
ArrayList<SaveState> saveStateArrayList,
SaveState previousState,
TextArea status)
throws IOException, Mate, CheckIsOpen, CastlingDone, ChangePawn {
// BufferedReader reader=new BufferedReader(new InputStreamReader(System.in));
while (!s.equals("exit")) {
saveStateArrayList.add(new SaveState(table, whitePlayer, blackPlayer));
previousState = saveStateArrayList.get(saveStateArrayList.size() - 1);
boolean nextToBlack = false;
System.out.println("White player moves: " + s);
// s = reader.readLine();
try {
new WhiteMove(s).move(table, whitePlayer, blackPlayer);
Cell myKingCell =
table.getOpponentKingCell(
WHITE, whitePlayer.getChessItemsMap(), blackPlayer.getChessItemsMap(), table);
// is Check to my king?
if (Move.isInAllItemsOfAvailableCellListBlack(
myKingCell, blackPlayer.getChessItemsMap(), table)) {
System.out.println("Black player will Announce you Check and Mate");
// Undo Last Move
previousState.undoHere(table, whitePlayer, blackPlayer);
// Undo Last Move
table.toString();
throw new CheckIsOpen();
}
// table.toString();
nextToBlack = true;
} catch (PlayerSameChessItem playerSameChessItem) {
System.out.println("Source & Target are the same");
} catch (EmptySourceCell emptySourceCell) {
System.out.println("Source Cell is empty");
} catch (InvalidSource invalidSource) {
System.out.println("Source is invalid");
} catch (NoCell noCell) {
} catch (InvalidMoveString invalidMoveString) {
System.out.println("String is invalid");
} catch (InvalidMove invalidMove) {
} catch (NoAvailableCells noAvailableCells) {
System.out.println("No Available Cells");
} /*catch (Check check) {
}*/
if (nextToBlack) {
// is Check or not?
Cell kingCell =
table.getOpponentKingCell(
BLACK, whitePlayer.getChessItemsMap(), blackPlayer.getChessItemsMap(), table);
if (Move.isInAllItemsOfAvailableCellListWhite(
kingCell, whitePlayer.getChessItemsMap(), table)) {
try {
throw new Check();
} catch (Check check) {
System.out.println("Check to Black Army");
// is Mate or not?
ArrayList<BlackTestMove> blackTestMoves = new ArrayList<>();
saveStateArrayList.add(new SaveState(table, whitePlayer, blackPlayer));
previousState = saveStateArrayList.get(saveStateArrayList.size() - 1);
for (SortedMap.Entry<String, ChessItem> item :
blackPlayer.getChessItemsMap().entrySet()) {
if (item.getValue() instanceof BlackKing) {
try {
for (Cell cell :
new BlackKingMoves(table.getCellByString(item.getKey()), table, true)
.getMoves()) {
blackTestMoves.add(
new BlackTestMove(
item.getValue().toString(), item.getKey(), cell.toString()));
}
} catch (NoAvailableCells noAvailableCells) {
}
}
if (item.getValue() instanceof BlackQueen) {
try {
for (Cell cell :
new BlackQueenMoves(table.getCellByString(item.getKey()), table).getMoves()) {
blackTestMoves.add(
new BlackTestMove(
item.getValue().toString(), item.getKey(), cell.toString()));
}
} catch (NoAvailableCells noAvailableCells) {
}
}
if (item.getValue() instanceof BlackBishop) {
try {
for (Cell cell :
new BlackBishopMoves(table.getCellByString(item.getKey()), table)
.getMoves()) {
blackTestMoves.add(
new BlackTestMove(
item.getValue().toString(), item.getKey(), cell.toString()));
}
} catch (NoAvailableCells noAvailableCells) {
}
}
if (item.getValue() instanceof BlackKnight) {
try {
for (Cell cell :
new BlackKnightMoves(table.getCellByString(item.getKey()), table)
.getMoves()) {
blackTestMoves.add(
new BlackTestMove(
item.getValue().toString(), item.getKey(), cell.toString()));
}
} catch (NoAvailableCells noAvailableCells) {
}
}
if (item.getValue() instanceof BlackPawn) {
try {
for (Cell cell :
new BlackPawnMoves(table.getCellByString(item.getKey()), table).getMoves()) {
blackTestMoves.add(
new BlackTestMove(
item.getValue().toString(), item.getKey(), cell.toString()));
}
} catch (NoAvailableCells noAvailableCells) {
}
}
if (item.getValue() instanceof BlackRook) {
try {
for (Cell cell :
new BlackRookMoves(table.getCellByString(item.getKey()), table).getMoves()) {
blackTestMoves.add(
new BlackTestMove(
item.getValue().toString(), item.getKey(), cell.toString()));
}
} catch (NoAvailableCells noAvailableCells) {
}
}
}
ArrayList<BlackTestMove> availableMoves = new ArrayList<>();
try {
if (blackTestMoves.size() > 0) {
for (BlackTestMove move : blackTestMoves) {
if (move.getChessItem().equals(Black.KING)) {
new BlackMove(move.getSource(), move.getDestination())
.move(table, whitePlayer, blackPlayer);
if (!(Move.isInAllItemsOfAvailableCellListWhite(
table.getCellByString(move.getDestination()),
whitePlayer.getChessItemsMap(),
table))) {
availableMoves.add(move);
}
previousState.undoHere(table, whitePlayer, blackPlayer);
} else {
new BlackMove(move.getSource(), move.getDestination())
.move(table, whitePlayer, blackPlayer);
if (!(Move.isInAllItemsOfAvailableCellListWhite(
kingCell, whitePlayer.getChessItemsMap(), table))) {
availableMoves.add(move);
}
previousState.undoHere(table, whitePlayer, blackPlayer);
}
}
if (availableMoves.size() == 0) {
throw new Mate(BLACK);
} else {
status.appendText("Available moves for black player are:\n");
System.out.println("Available moves for black player are:");
for (BlackTestMove move : availableMoves) {
status.appendText(move.toString() + "\n");
System.out.println(move.toString());
}
}
}
} catch (NoAvailableCells noAvailableCells) {
} catch (NoCell noCell) {
} catch (InvalidMove invalidMove) {
} catch (PlayerSameChessItem playerSameChessItem) {
} catch (EmptySourceCell emptySourceCell) {
} catch (InvalidSource invalidSource) {
}
}
}
saveState = new SaveState(table, whitePlayer, blackPlayer);
table.toString();
break;
}
}
}