How to encode a chess deadlock rule?

Question

I am trying to write a chess game and find that I cannot find a solution to find a deadlock. I'm trying google but can't find anything. Is there a known algorithm or something else?

Answer 1

Your motion generator will be one of two different designs;

• or he checks the legality when creating moves
• or you create all possible actions and then delete those that are illegal.

The first is better, since it does not need further processing.

The dead end condition is simply one where there are no legal moves, and the king of the moving side is not . The checkmate condition is a condition in which there are no legal moves, but the king of the moving side .

In other words, if you figured out how to detect a check and checkmate, you already have everything you need to detect a dead end.

Answer 2

Here is an open source code with all the rules of a classic chess game: https://github.com/cjortegon/basic-chess

You can start the project immediately after cloning the project (Android, iOS, Desktop and Web), or you can use the basic logic, which is located here: https://github.com/cjortegon/basic-chess/tree/master/libgdx/core / src / com / mountainreacher / chess / model

I based my decision on an algorithm with three points, the first moment is when the player selects a part from the board, and then when the destination of this piece is selected and finally when the piece reaches this position (given that this is an animated game, if not, you can combine steps 2 and 3).

The following code is implemented in Java. From the properties of the model class:

boolean turn; GenericPiece selected, conquest; ClassicBoard board; List<int[]> possibleMovements; int checkType; 

The first method will process moments 1, 2 and the special moment of “conquest” (applies only to the workpiece):

 public boolean onCellClick(int row, int column) { if (row == -1 && conquest != null) { checkType = 0; conquest.changeFigure(column); return true; } else if (selected != null) { if (possibleMovements != null) { for (int[] move : possibleMovements) { if (move[0] == row && move[1] == column) { // Move the PieceActor to the desired position if (selected.moveTo(row, column)) { turn = !turn; } break; } } } selected = null; possibleMovements = null; return true; } else { selected = board.getSelected(turn ? Piece.WHITE_TEAM : Piece.BLACK_TEAM, row, column); if (selected != null) { possibleMovements = new ArrayList<>(); possibleMovements.addAll(((GenericPiece) selected).getMoves(board, false)); // Checking the movements board.checkPossibleMovements(selected, possibleMovements); if (possibleMovements.size() == 0) { possibleMovements = null; selected = null; return false; } else { return true; } } } return false; } 

And the following method will handle the third point (when the animation ends):

 public void movedPiece(Piece piece) { Gdx.app.log(TAG, "movedPiece(" + piece.getType() + ")"); // Killing the enemy Piece killed = board.getSelectedNotInTeam(piece.getTeam(), piece.getRow(), piece.getColumn()); if (killed != null) { killed.setAvailable(false); } // Checking hacks GenericPiece[] threat = board.kingIsInDanger(); if (threat != null) { checkType = board.hasAvailableMoves(threat[0].getTeam()) ? CHECK : CHECK_MATE; } else { checkType = NO_CHECK; } // Checking castling if (piece.getFigure() == Piece.ROOK && ((GenericPiece) piece).getMovesCount() == 1) { Piece king = board.getSelected(piece.getTeam(), piece.getRow(), piece.getColumn() + 1); if (king != null && king.getFigure() == Piece.KING && ((GenericPiece) king).getMovesCount() == 0) { // Left Rook if (board.getSelected(piece.getRow(), piece.getColumn() - 1) == null) { king.moveTo(piece.getRow(), piece.getColumn() - 1); } } else { king = board.getSelected(piece.getTeam(), piece.getRow(), piece.getColumn() - 1); if (king != null && king.getFigure() == Piece.KING && ((GenericPiece) king).getMovesCount() == 0) { // Right Rook if (board.getSelected(piece.getRow(), piece.getColumn() + 1) == null) { king.moveTo(piece.getRow(), piece.getColumn() + 1); } } } } // Conquest else if (piece.getFigure() == Piece.PAWN && (piece.getRow() == 0 || piece.getRow() == board.getRows() - 1)) { conquest = (GenericPiece) piece; checkType = CONQUEST; } } 

This code covers all the rules of classical chess, including: regular pieces, castling, check, checkmate and winning pawns.