//Determine if player still have escape moves for the king or not
private bool hasEscapedMoves()
{
foreach (Move move in this.legalMoves)
{
MoveTransition transition = this.makeMove(move);
if (transition.getMoveStatus().isDone())
{
return(true);
}
}
return(false);
}
private int maxValue(Board board, int depth, int alpha, int beta)
{
if (depth == 0 || BoardUtils.isBoardinStaleMateorCheckMate(board))
{
return(this.heuristic.calculate(board, depth));
}
int value = Int32.MinValue;
//Find state in transposition table
int key = this.table.hash(board);
if (this.table.getNode(key, depth, board) != null)
{
return(this.table.getNode(key, depth, board).Value);
}
//If the current state is not in TT then run minimax;
Move bestMove = null;
foreach (Move move in board.CurrentPlayer.getLegalMoves())
{
nodeCount++;
MoveTransition trans = board.CurrentPlayer.makeMove(move);
if (trans.getMoveStatus().isDone())
{
int temp = minValue(trans.ToBoard, depth - 1, alpha, beta);
if (temp > value)
{
value = temp;
bestMove = move;
}
if (value > beta)
{
this.table.add(key, new Node(bestMove, value, depth, board));
return(value);
}
alpha = Math.Max(alpha, value);
}
}
this.table.add(key, new Node(bestMove, value, depth, board));
return(value);
}
private Move findMove(Board board, int depth)
{
nodeCount = 0;
int alpha = Int32.MinValue;
int beta = Int32.MaxValue;
//Find state in transposition table
Move bestMove = null;
int key = this.table.hash(board);
if (this.table.getNode(key, depth, board) != null)
{
Node node = this.table.getNode(key, depth, board);
return(node.BestMove);
}
//If the current state is not in TT then run minimax;
int currentValue;
if (board.CurrentPlayer.getAlliance() == Sides.BLACK)
{
currentValue = Int32.MaxValue;
}
else
{
currentValue = Int32.MinValue;
}
foreach (Move move in board.CurrentPlayer.getLegalMoves())
{
nodeCount++;
MoveTransition trans = board.CurrentPlayer.makeMove(move);
if (trans.getMoveStatus().isDone())
{
if (board.CurrentPlayer.getAlliance() == Sides.BLACK)
{
int temp = maxValue(trans.ToBoard, depth - 1, alpha, beta);
if (temp < currentValue)
{
currentValue = temp;
bestMove = move;
}
beta = Math.Min(beta, currentValue);
}
else
{
int temp = minValue(trans.ToBoard, depth - 1, alpha, beta);
if (temp > currentValue)
{
currentValue = temp;
bestMove = move;
}
alpha = Math.Max(alpha, currentValue);
}
}
}
/*Console.Write("NODES: ");
* Console.WriteLine(nodeCount);
* Console.WriteLine(currentValue);*/
table.add(key, new Node(bestMove, currentValue, depth, board));
return(bestMove);
}