126 lines
3.4 KiB
OCaml
126 lines
3.4 KiB
OCaml
type grid = { grid : char array; width : int; height : int }
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let grid_make posmap_fn strs =
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let grid =
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List.fold_left String.cat "" strs
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|> posmap_fn |> String.to_seq |> Array.of_seq
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in
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let height = List.length strs in
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let width = Array.length grid / height in
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Printf.printf "width %d height %d \n" width height;
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{ grid; width; height }
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let[@warning "-32"] grid_print grid =
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Array.iteri
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(fun i c ->
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print_char c;
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if i mod grid.width = grid.width - 1 then print_newline ())
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grid.grid
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let find_start_idx grid =
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match Array.find_index (( = ) '@') grid.grid with
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| None -> failwith "find_start_idx"
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| Some x -> x
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let instrs_of_file fname =
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let strs = Aoc.strings_of_file fname in
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let rec impl acc = function
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| [] | "" :: [] -> failwith "instrs_of_file.impl"
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| "" :: t -> (List.rev acc, t)
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| h :: t -> impl (h :: acc) t
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in
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let grid, moves = impl [] strs in
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(grid, List.fold_left String.cat "" moves |> String.to_seq |> List.of_seq)
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let rec move_robot_x grid i di =
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match grid.grid.(i + di) with
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| '#' -> i
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| 'O' | '[' | ']' ->
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if move_robot_x grid (i + di) di = i + di then i
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else move_robot_x grid i di
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| '.' ->
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grid.grid.(i + di) <- grid.grid.(i);
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grid.grid.(i) <- '.';
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i + di
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| _ -> failwith "move_robot_x"
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let rec can_move_y grid i di =
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match grid.grid.(i + di) with
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| '#' -> false
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| '.' -> true
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| 'O' -> can_move_y grid (i + di) di
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| '[' -> can_move_y grid (i + di) di && can_move_y grid (i + di + 1) di
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| ']' -> can_move_y grid (i + di - 1) di && can_move_y grid (i + di) di
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| _ -> failwith "can_move_y"
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let move_robot_y grid i di =
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let rec do_move i =
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match grid.grid.(i + di) with
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| '#' -> failwith "move_robot_y.do_move #"
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| '.' ->
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grid.grid.(i + di) <- grid.grid.(i);
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grid.grid.(i) <- '.'
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| 'O' ->
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do_move (i + di);
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do_move i
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| '[' ->
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do_move (i + di);
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do_move (i + di + 1);
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do_move i
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| ']' ->
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do_move (i + di - 1);
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do_move (i + di);
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do_move i
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| _ -> failwith "move_robot_y.do_move"
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in
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if can_move_y grid i di then (
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do_move i;
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i + di)
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else i
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let process_move grid robot dir =
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(*grid_print grid;
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Printf.printf "\nMove: %c\n" dir;*)
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match dir with
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| '^' -> move_robot_y grid robot ~-(grid.width)
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| 'v' -> move_robot_y grid robot grid.width
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| '<' -> move_robot_x grid robot ~-1
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| '>' -> move_robot_x grid robot 1
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| _ -> failwith "process_move"
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let rec process_moves grid robot = function
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| [] -> grid
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| h :: t -> process_moves grid (process_move grid robot h) t
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let calc_score grid =
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Array.mapi
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(fun idx c ->
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if c = 'O' || c = '[' then
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(idx mod grid.width) + (100 * (idx / grid.width))
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else 0)
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grid.grid
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|> Array.fold_left ( + ) 0
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let expand_grid str =
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let b = Buffer.create (String.length str * 2) in
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let add_c = function
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| '#' -> Buffer.add_string b "##"
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| 'O' -> Buffer.add_string b "[]"
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| '.' -> Buffer.add_string b ".."
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| '@' -> Buffer.add_string b "@."
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| _ -> failwith "expand_grid"
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in
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String.iter add_c str;
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Buffer.contents b
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let part posmap_fn (grid, moves) =
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let grid = grid_make posmap_fn grid in
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let robot = find_start_idx grid in
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let _ = process_moves grid robot moves in
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(*grid_print grid;*)
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calc_score grid
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let _ =
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Aoc.main instrs_of_file
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[ (string_of_int, part Fun.id); (string_of_int, part expand_grid) ]
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