private Int32 RunRecursive(ChessBoard myBoard, Int16 depth, ChessPiece turn)
{
List<ChessMove> moves = myBoard.GetAllMoves(turn);
if (moves.Count == 0)
{
if (turn == this.MySuit)
{
// I am mated or stale mated
return this.Board.InCheck(turn) ? -WonScore : StaleMateScore;
}
else
{
// Opponent is mated or stale mated
return this.Board.InCheck(turn) ? WonScore : StaleMateScore;
}
}
Int32 evaluation;
Int32 bestEvaluation = LowestScore;
ChessPiece capturedChessPiece;
foreach (ChessMove move in moves)
{
myBoard.DoMove(move, out capturedChessPiece);
if (depth > 1)
{
// Pre evaluation to determine cut
evaluation = TryGetCachedEvaluation(myBoard, 1, () =>
{
return Evaluate(myBoard, turn, depth);
});
if (evaluation > this.CutLimit)
{
myBoard.UndoMove(move, capturedChessPiece);
return evaluation;
}
// Full evaluation
evaluation = TryGetCachedEvaluation(myBoard, depth, () =>
{
return -RunRecursive(myBoard, (short)(depth - 1), turn == ChessPiece.White ? ChessPiece.Black : ChessPiece.White);
});
}
else
{
evaluation = TryGetCachedEvaluation(myBoard, depth, () =>
{
return Evaluate(myBoard, turn, depth);
});
}
if (evaluation > bestEvaluation)
{
bestEvaluation = evaluation;
}
myBoard.UndoMove(move, capturedChessPiece);
}
return bestEvaluation;
}
private Int32 RunRecursive(ChessBoard myBoard, Int16 depth, ChessPiece turn,
Int32 alpha, Int32 beta, bool maximizingPlayer)
{
if (depth == 0)
{
return TryGetCachedEvaluation(myBoard, 0, () =>
{
return Evaluate(myBoard, turn, 0);
});
}
List<ChessMove> moves = myBoard.GetAllMoves(turn);
ChessPiece capturedChessPiece;
Int32 evaluation;
if (maximizingPlayer)
{
evaluation = Int32.MinValue;
foreach (var move in moves)
{
myBoard.DoMove(move, out capturedChessPiece);
int logPos = GetLogPos();
var e = TryGetCachedEvaluation(myBoard, depth, () =>
{
return RunRecursive(myBoard, (short)(depth - 1), turn == ChessPiece.White ? ChessPiece.Black : ChessPiece.White,
alpha, beta, false);
});
evaluation = Math.Max(evaluation, e);
Log(depth, "<m t=\"max\" d=\"" + (this.MaxDepth-depth) +"\" m=\"" + move.ToString() + "\" e=\"" + e + "\">", logPos);
Log(depth, "</m>");
myBoard.UndoMove(move, capturedChessPiece);
if (evaluation > alpha)
{
Log(depth, "<a>" + evaluation + " gt " + alpha + "</a>");
}
alpha = Math.Max(alpha, evaluation);
if (beta <= alpha)
{
Log(depth, "<c>" + beta + " lte " + alpha + "</c>");
break;
}
}
}
else
{
evaluation = Int32.MaxValue;
foreach (var move in moves)
{
myBoard.DoMove(move, out capturedChessPiece);
int logPos = GetLogPos();
var e = TryGetCachedEvaluation(myBoard, depth, () =>
{
return RunRecursive(myBoard, (short)(depth - 1), turn == ChessPiece.White ? ChessPiece.Black : ChessPiece.White,
alpha, beta, true);
});
evaluation = Math.Min(evaluation, e);
Log(depth, "<m t=\"min\" d=\"" + (this.MaxDepth - depth) + "\" m=\"" + move.ToString() + "\" e=\"" + e + "\">", logPos);
Log(depth, "</m>");
myBoard.UndoMove(move, capturedChessPiece);
if (evaluation < beta)
{
Log(depth, "<b>" + evaluation + " lt " + beta + "</b>");
}
beta = Math.Min(beta, evaluation);
if (beta <= alpha)
{
Log(depth, "<c>" + beta + " lte " + alpha + "</c>");
break;
}
}
}
return evaluation;
}