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Tic tac toe using alpha beta ghosts in java

I am trying to play tic tac using an iterative alpha beta attack. I have one second limit for movement, but for some reason it does not work.

I changed the usual alpha beta code, so instead of returning alpha or beta, it returns a state (which is a board with the following movement)

Every time I create children, I update their depth.

But for some reason, I keep losing, and I see that my alpha beta doesn't see a better way to do it.

Here is my code:

Outer loop:

while (watch.get_ElapsedMilliseconds() < 900 && d <= board.length * board[0].length - 1)
        {
            s = maxiMin(beginSt, d, watch);
            if (s.getNextMove().getIsWin() == true)
            {
                break;
            }
            d++;
        }
        return new location(s.getNextMove().getRow(), s.getNextMove().getCol());

Alpha beta:

public State maxiMin(State s, int depth, Stopwatch timer)
    {
        if (s.getDepth() == 7)
        {
            Console.WriteLine();
        }
        if (timer.get_ElapsedMilliseconds() > 850 || s.getDepth() == depth || goalTest(s.getBoard()) != 0)
        {
            s.evaluationFunc(line_length, PlayerShape);
            s.setAlpha(s.getEvaluation());
            s.setBeta(s.getEvaluation());
            return s;
        }
        LinkedList<State> children = createChildren(s, true);
        // No winner, the board is full
        if (children.get_Count() == 0)
        {
            s.evaluationFunc(line_length, PlayerShape);
            s.setAlpha(s.getEvaluation());
            s.setBeta(s.getEvaluation());
            return s;
        }
        while (children.get_Count() > 0)
        {
            State firstChild = children.get_First().get_Value();
            children.RemoveFirst();
            State tmp = miniMax(firstChild, depth, timer);
            int value = tmp.getBeta();
            if (value > s.getAlpha())
            {
                s.setAlpha(value);
                s.setNextMove(tmp);
            }
            if (s.getAlpha() >= s.getBeta())
            {
                return s;
            }
        }
        return s;
    }

    public State miniMax(State s, int depth, Stopwatch timer)
    {
        if (s.getDepth() == 7)
        {
            Console.WriteLine();
        }
        if (timer.get_ElapsedMilliseconds() > 850 || s.getDepth() == depth || goalTest(s.getBoard()) != 0)
        {
            s.evaluationFunc(line_length, PlayerShape);
            s.setAlpha(s.getEvaluation());
            s.setBeta(s.getEvaluation());
            return s;
        }
        LinkedList<State> children = createChildren(s, false);
        // No winner, the board is full
        if (children.get_Count() == 0)
        {
            s.evaluationFunc(line_length, PlayerShape);
            s.setAlpha(s.getEvaluation());
            s.setBeta(s.getEvaluation());
            return s;
        }
        while (children.get_Count() > 0)
        {
            State firstChild = children.get_First().get_Value();
            children.RemoveFirst();
            State tmp = maxiMin(firstChild, depth, timer);
            int value = tmp.getAlpha();
            if (value < s.getBeta())
            {
                s.setBeta(value);
                s.setNextMove(tmp);
            }
            if (s.getAlpha() >= s.getBeta())
            {
                return s;
            }
        }
        return s;
    }

It would be helpful if someone would tell me if something is wrong. I suspect, maybe this is somehow connected with the fact that I come back “instead of”, instead of the usual alpha-beta, which returns a score, but I could not find the error.

Thanks in advance,

Lena

+5
1

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