@Override
protected Integer chooseMoveDepthLimited(int counter) {
ValCol result;
System.out.println("Choosing move depth limited, det");
int offset = 10;
result =
negaMaxWithABPruning /* DepthDiscounting */(
0, counter, 1, Integer.MIN_VALUE + offset, Integer.MAX_VALUE - offset);
return (result == null ? null : result.getCol());
}
private ValCol negaMaxWithABPruning(int depth, int counter, int sign, int alpha, int beta) {
if (isStopSignaled) {
return null;
}
if (boardCopy.gameOver() || depth == depthLimit) {
int util = (int) (Math.pow(discountFactor, depth) * sign * boardCopy.getAnalysis(counter));
return new ValCol(util, -1); // col doesn't matter since search depth
// will never be 0
}
int col = 0;
int i = 0;
while (i < 7 && alpha < beta) {
if (boardCopy.findDepth(i) > -1) {
if (sign == 1) {
boardCopy.placeCounter(i, counter);
} else {
boardCopy.placeCounter(i, 3 - counter);
}
ValCol vc = negaMaxWithABPruning(depth + 1, counter, -sign, -beta, -alpha);
if (vc == null) {
return null;
}
boardCopy.undoMove();
int x = -vc.getVal();
if (x > alpha) {
alpha = x;
col = i;
}
}
i++;
}
return new ValCol(alpha, col);
}