private static float AlphaBeta(GameState gs, int depth, float alpha, float beta, bool isMax)
{
if (depth == 0 || gs.IsEndGame()) {
float val = EvaluateMove(gs);
return isMax ? val : -val;
}
Point p = null;
if (isMax) {
p = new Point(gs.MyX(), gs.MyY());
} else {
p = new Point(gs.OpponentX(), gs.OpponentY());
}
GameState newState = null;
foreach (Point child in gs.PossibleMoves(p.X, p.Y, true)) {
if (isMax) {
newState = gs.ApplyMoveToMeAndCreate(child.GetDirectionFromPoint(p.X, p.Y));
} else {
newState = gs.ApplyMoveToOpponentAndCreate(child.GetDirectionFromPoint(p.X, p.Y));
}
alpha = Math.Max (alpha, -AlphaBeta(newState, depth-1, -beta, -alpha, !isMax));
if (beta <= alpha) {
break;
}
}
return alpha;
}