84 lines
2.6 KiB
Prolog
84 lines
2.6 KiB
Prolog
% Read a file with the puzzle and return the initial state of the game
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read_board(Filename, Board) :-
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open(Filename, read, Stream),
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read_lines(Stream, Lines),
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maplist(atom_chars, Board, Lines).
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read_lines(Stream, []) :-
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at_end_of_stream(Stream).
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read_lines(Stream, [Line|Lines]) :-
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\+ at_end_of_stream(Stream),
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read_line(Stream, Line),
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read_lines(Stream, Lines).
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read_line(Stream, Line) :-
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read_line_to_codes(Stream, Codes),
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maplist(char_code, Line, Codes).
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% Solve the Sokoban puzzle using DFS
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sokoban(Board, Moves, Solution) :-
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solved(Board),
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Solution = Board,
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Moves = [].
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sokoban(Board, Moves, Solution) :-
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move(Board, Dir, NewBoard),
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\+ member(NewBoard, Moves),
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sokoban(NewBoard, [NewBoard|Moves], Solution1),
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Solution = [Dir|Solution1].
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% Check if the board is solved (all boxes are on targets)
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solved(Board) :-
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findall(Box, (member(Box, Board), member($, Box)), Boxes),
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findall(Target, (member(Target, Board), member(., Target)), Targets),
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subset(Boxes, Targets).
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% Find the position of the player on the board
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player(Board, row(Row), col(Col)) :-
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nth0(Row, Board, RowList),
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nth0(Col, RowList, '1').
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% Find the cell at the given row and column
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cell(Board, row(Row), col(Col), Cell) :-
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nth0(Row, Board, RowList),
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nth0(Col, RowList, Cell).
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% Move the player in the given direction
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% If the player pushes a box, move the box as well
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move(Board, Dir, NewBoard) :-
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player(Board, row(Row), col(Col)),
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cell(Board, row(NewRow), col(NewCol), Cell),
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direction(Dir, dRow, dCol),
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NewRow is Row + dRow,
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NewCol is Col + dCol,
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(
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Cell = ' ' ; Cell = '.',
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replace(Board, Row, Col, ' ', Board1),
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replace(Board1, NewRow, NewCol, '1', NewBoard)
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;
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Cell = '$' ; Cell = '*',
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cell(Board, row(NewRow2), col(NewCol2), Cell2),
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NewRow2 is NewRow + dRow,
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NewCol2 is NewCol + dCol,
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(Cell2 = ' ' ; Cell2 = '.'),
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replace(Board, Row, Col, ' ', Board1),
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replace(Board1, NewRow, NewCol, '1', Board2),
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replace(Board2, NewRow2, NewCol2, '$', NewBoard)
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).
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% Replace an element at the given row and column
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replace(List, Row, Col, NewElem, NewList) :-
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nth0(Row, List, RowList),
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nth0(Col, RowList, _, RestRow),
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nth0(Col, NewRow, NewElem, RestRow),
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nth0(Row, NewList, NewRow, RestList).
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% Define the directions
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direction(up, -1, 0).
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direction(down, 1, 0).
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direction(left, 0, -1).
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direction(right, 0, 1).
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% Example usage
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solve_sokoban(Filename, Solution) :-
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read_board(Filename, Board),
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sokoban(Board, [Board], Solution).
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