@Override
protected MoveValuePair ABMaxMinValue(
Position position, int depth, int alpha, int beta, boolean maxTurn)
throws IllegalMoveException {
if (depth <= 0 || position.isTerminal()) {
return handleTerminal(position, maxTurn, alpha, beta);
} else {
MoveValuePair bestMove = new MoveValuePair();
LinkedList<MoveValuePair> sortedMoves = getSortedMoves(position, maxTurn);
for (MoveValuePair movepair : sortedMoves) {
short move = movepair.move;
// collect values from further moves
// get and update transposition table if possible
position.doMove(move);
if (this.p2tte.containsKey(position.getHashCode())
&& (this.p2tte.get(position.getHashCode()).depth >= depth)) {
// System.out.println("trans table at level: " + depth);
TransTableEntry tte = p2tte.get(position.getHashCode());
bestMove.updateMinMax(move, tte.eval, maxTurn);
} else {
// recursive method
MoveValuePair childMove = ABMaxMinValue(position, depth - 1, alpha, beta, !maxTurn);
bestMove.updateMinMax(move, childMove.eval, maxTurn);
p2tte.put(position.getHashCode(), new TransTableEntry(childMove.eval, depth, move));
}
position.undoMove();
// update the alpha beta boundary
if (maxTurn) alpha = bestMove.eval;
else beta = bestMove.eval;
// prune the subtree if needed
if (alpha >= beta) return bestMove;
}
return bestMove;
}
}
// protected MoveValuePair handleTerminal(Position position, boolean maxTurn) {
// MoveValuePair finalMove = new MoveValuePair();
// if (position.isTerminal() && position.isMate()) {
// this.terminalFound = position.isTerminal();
// finalMove.eval = (maxTurn ? BE_MATED : MATE);
// } else if (position.isTerminal() && position.isStaleMate())
// finalMove.eval = 0;
// else {
// finalMove.eval = (int) ( (position.getMaterial() + position.getDomination()));
// }
//// System.out.print(finalMove.eval + " ");
// return finalMove;
// }
protected LinkedList<MoveValuePair> getCapturingSortedMoves(Position position, boolean maxTurn)
throws IllegalMoveException {
LinkedList<MoveValuePair> sortedMoves = new LinkedList<MoveValuePair>();
short[] moves = position.getAllCapturingMoves();
MoveValuePair theMove = null;
ASCENDING = maxTurn ? false : true;
for (short move : moves) {
position.doMove(move);
if (p2tte.containsKey(position.getHashCode())) {
theMove = new MoveValuePair(move, p2tte.get(position.getHashCode()).eval);
} else {
// for max turn, I assign worst values those unvisited positions
// theMove = new MoveValuePair(move, maxTurn ? BE_MATED : MATE);
int eval = (int) ((maxTurn ? -1 : 1) * (position.getMaterial() + position.getDomination()));
theMove = new MoveValuePair(move, eval);
}
position.undoMove();
sortedMoves.add(theMove);
}
Collections.sort(
sortedMoves,
new Comparator<MoveValuePair>() {
@Override
public int compare(MoveValuePair c1, MoveValuePair c2) {
// System.out.println(c1.eval + " vs " + c2.eval);
return (int) ((ASCENDING ? 1 : -1) * Math.signum(c1.eval - c2.eval)); // use your logic
}
});
return sortedMoves;
}
/**
* Returns whether the given position occurs in the main line of this game.
*
* @param position the position to look for, must not be null
* @return whether the given position occurs in the main line of this game
*/
public boolean containsPosition(ImmutablePosition position) {
boolean res = false;
int index = getCurNode();
gotoStart(true);
for (; ; ) {
if (m_position.getHashCode() == position.getHashCode()) {
res = true;
break;
}
if (!hasNextMove()) break;
goForward(true);
}
gotoNode(index, true);
return res;
}
