48 lines
1.3 KiB
OCaml
48 lines
1.3 KiB
OCaml
let find_pos map =
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let rec impl row =
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if row >= Array.length map then failwith "find_pos"
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else
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match Array.find_index (fun x -> x = '^') map.(row) with
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| Some i -> (i, row)
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| None -> impl (row + 1)
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in
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impl 0
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let read_file fname =
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let lst = Aoc.strings_of_file fname in
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let map1 = Array.of_list lst in
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let map2 =
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Array.map (fun s -> Array.init (String.length s) (String.get s)) map1
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in
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let pos = find_pos map2 in
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(map2, pos, (0, -1))
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let is_valid_pos map (x, y) =
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if y < 0 || y >= Array.length map then false
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else if x < 0 || x >= Array.length map.(y) then false
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else true
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let rec move (map, (x, y), (dx, dy)) =
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let () = map.(y).(x) <- 'X' in
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let x', y' = (x + dx, y + dy) in
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if is_valid_pos map (x', y') && map.(y').(x') = '#' then
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move (map, (x, y), (-dy, dx))
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else (map, (x', y'), (dx, dy))
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let part1 (map, pos, vel) =
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let rec impl (map, pos, vel) =
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if is_valid_pos map pos then impl (move (map, pos, vel)) else (map, pos, vel)
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in
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let _ = impl (map, pos, vel) in
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Array.iter
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(fun y ->
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Array.iter (fun x -> print_char x) y;
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print_newline ())
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map;
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Array.fold_left
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(fun acc y ->
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Array.fold_left (fun acc x -> if x = 'X' then acc + 1 else acc) acc y)
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0 map
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let _ = Aoc.main read_file [ (string_of_int, part1) ]
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