private double MaxValue(int depth, double alpha, double beta, ChessEngine.Engine.Engine engine)
{
//Check if stalemate
if (engine.IsStalemateBy50MoveRule())
{
return(0);
}
//Check if checkmate
if (engine.IsCheckMate())
{
return(Double.MinValue);
}
//A leaf node, return value of board state
if ((depth == 0 && maxDepth != 0) || (maxTime.Seconds != 0 && timer.Elapsed > maxTime))
{
if (maxTime.Seconds != 0 && timer.Elapsed > maxTime)
{
overTime = true;
}
double boardValue = evaluator.ValuateBoard(engine.ChessBoard.Squares);
return(boardValue);
}
double value = Double.MinValue;
//Find all pieces that can be moved on this turn
DynamicArray pieceList = ReturnAllMovablePieces(engine);
//Go through all possible moves
foreach (byte piece in pieceList)
{
foreach (byte move in engine.ChessBoard.Squares[piece].Piece.ValidMoves)
{
//Create the next board stage
ChessEngine.Engine.Engine newState = ReturnNewState(engine, piece, move);
//Invalid move, continue to next move
if (newState == null)
{
continue;
}
//Pass parameters to the next node
value = MinValue(depth - 1, alpha, beta, newState);
//Check if alpha can be given bigger value
if (value > alpha)
{
alpha = value;
if (depth == maxDepth)
{
//Back at the root node with a better move than the previous best
byte[] source = engine.CalculateColumnAndRow(piece);
byte[] destination = engine.CalculateColumnAndRow(move);
bestMove.SourceColumn = source[0];
bestMove.SourceRow = source[1];
bestMove.DestinationColumn = destination[0];
bestMove.DestinationRow = destination[1];
}
}
//If alpha is bigger than beta, don't investigate branch further
if (alpha > beta)
{
return(alpha);
}
if (overTime)
{
break;
}
}
if (overTime)
{
break;
}
}
return(alpha);
}
private double MinValue(int depth, double alpha, double beta, ChessEngine.Engine.Engine engine)
{
//Check if stalemate
if (engine.IsStalemateBy50MoveRule())
{
return(0);
}
//Check if checkmate
if (engine.IsCheckMate())
{
return(Double.MaxValue);
}
//A leaf node, return value of board state
if ((depth == 0 && maxDepth != 0) || (maxTime.Seconds != 0) && timer.Elapsed > maxTime)
{
if (maxTime.Seconds != 0 && timer.Elapsed > maxTime)
{
overTime = true;
}
double boardValue = evaluator.ValuateBoard(engine.ChessBoard.Squares);
return(boardValue);
}
double value = Double.MaxValue;
//Find all pieces that can be moved on this turn
DynamicArray pieceList = ReturnAllMovablePieces(engine);
//Go through all possible moves
foreach (byte piece in pieceList)
{
foreach (byte move in engine.ChessBoard.Squares[piece].Piece.ValidMoves)
{
//Create the next board stage and pass it to the next node
ChessEngine.Engine.Engine newState = ReturnNewState(engine, piece, move);
//Invalid move, continue to next move
if (newState == null)
{
continue;
}
value = MaxValue(depth - 1, alpha, beta, newState);
//Check if beta can be given smaller value
if (value < beta)
{
beta = value;
}
//If beta is smaller than alpha, don't investigate branch further
if (beta < alpha)
{
return(beta);
}
if (overTime)
{
break;
}
}
if (overTime)
{
break;
}
}
return(beta);
}
