private async Task <Move> NegamaxRoot(NegamaxContext context, double alpha, double beta, int depth, int color, CancellationToken aiCancelToken)
{
IEnumerable <NegamaxContext> orderedAnalysis = GetSortedMoves(context.Board, color, aiCancelToken);
double bestScore = MinValue;
Move localBestMove = orderedAnalysis.First().Move;
foreach (var nextContext in orderedAnalysis)
{
if (aiCancelToken.IsCancellationRequested)
{
return(localBestMove);
}
double score = -(await Negamax(nextContext, -beta, -alpha, depth - 1, -color, aiCancelToken));
if (score > bestScore)
{
localBestMove = nextContext.Move;
}
bestScore = Math.Max(bestScore, score);
alpha = Math.Max(alpha, score);
if (alpha >= beta)
{
break;
}
}
;
return(localBestMove);
}
public async Task <Move> PickBestMoveAsync(Board board, CancellationToken aiCancelToken)
{
var initialContext = new NegamaxContext(null, board, 0, false);
Move bestMove = await NegamaxRoot(initialContext, MinValue, MaxValue, _depth, isPlayer1? 1 : -1, aiCancelToken);
return(bestMove);
}
public Move PickBestMove(Board board)
{
var cancelSource = new CancellationTokenSource();
var initialContext = new NegamaxContext(null, board, 0, false);
Move bestMove = NegamaxRoot(initialContext, MinValue, MaxValue, 3, isPlayer1 ? 1 : -1, cancelSource.Token).Result;
return(bestMove);
}
public async Task <Move> PickBestMoveAsync(Board board, CancellationToken aiCancelToken)
{
// calc all the possible next boards
List <Board> nextBoards = new List <Board>();
foreach (var move in board.GetAvailableMovesForCurrentPlayer())
{
nextBoards.Add(Board.ComputeFutureBoard(board, move));
}
var initialContext = new NegamaxContext(null, board, 0, false);
Move bestMove = await NegamaxRoot(initialContext, MinValue, MaxValue, 3, isPlayer1? 1 : -1, aiCancelToken);
return(bestMove);
}
private async Task <double> Negamax(NegamaxContext context, double alpha, double beta, int depth, int color, CancellationToken aiCancelToken)
{
if (depth == 0 || !context.Board.IsPlayable)
{
if (context.ScoreCalculated)
{
return(context.Score * color);
}
else
{
return(_analyzer.Analyze(context.Board).player1Advantage *color);
}
}
IEnumerable <NegamaxContext> orderedAnalysis = GetSortedMoves(context.Board, color, aiCancelToken);
double bestScore = MinValue;
foreach (var nextContext in orderedAnalysis)
{
double score = -(await Negamax(nextContext, -beta, -alpha, depth - 1, -color, aiCancelToken));
bestScore = Math.Max(bestScore, score);
alpha = Math.Max(alpha, score);
if (alpha >= beta)
{
break;
}
if (aiCancelToken.IsCancellationRequested)
{
return(bestScore);
}
}
;
return(bestScore);
}