private static ScorePair AlphaBetaMax(ChessBoard chessBoard, int alpha, int beta, int depth)
{
if (depth == 0)
{
return(new ScorePair(CountScore(chessBoard, chessBoard.CurrentPlayer), null));
}
Serializator ser = new Serializator();
List <Tuple <ChessPiece, Tuple <int, int> > > allMovesThisTurn = chessBoard
.GetAllPossibleMoves()
.FindAll(chessPieceNMoves => chessPieceNMoves.Item1.GetPlayer() == chessBoard.CurrentPlayer);
MovePair bestMove = null;
foreach (var move in allMovesThisTurn)
{
ChessBoard chessBoardCopy = ser.DeepCopy(chessBoard);
var thisMove = new MovePair(move.Item1.Position, move.Item2);
if (chessBoardCopy.MovePiece(thisMove.Item1, thisMove.Item2))
{
var score = AlphaBetaMin(chessBoardCopy, alpha, beta, depth - 1).Item1;
if (score >= beta)
{
return(new ScorePair(beta, null)); // fail hard beta-cutoff
}
if (score > alpha)
{
alpha = score; // alpha acts like max in MiniMax
bestMove = thisMove;
}
}
}
return(new ScorePair(alpha, bestMove));
}
private static ScorePair NegaMax(ChessBoard chessBoard, int depth,
MovePair lastMove = null)
{
Serializator ser = new Serializator();
if (depth == 0)
{
return(new Tuple <int, MovePair>(
CountScore(chessBoard, chessBoard.CurrentPlayer), lastMove));
}
ScorePair maxS = new ScorePair(Int32.MinValue, null);
List <Tuple <ChessPiece, Tuple <int, int> > > allMovesThisTurn = chessBoard
.GetAllPossibleMoves()
.FindAll(chessPieceNMoves => chessPieceNMoves.Item1.GetPlayer() == chessBoard.CurrentPlayer);
foreach (var move in allMovesThisTurn)
{
ChessBoard chessBoardCopy = ser.DeepCopy(chessBoard);
var thisMove = new MovePair(move.Item1.Position, move.Item2);
if (chessBoardCopy.MovePiece(thisMove.Item1, thisMove.Item2))
{
int score = -NegaMax(chessBoardCopy, depth - 1, thisMove).Item1;
if (score > maxS.Item1)
{
maxS = new ScorePair(score, thisMove);
}
}
}
return(maxS);
}