51 lines
1.3 KiB
OCaml
51 lines
1.3 KiB
OCaml
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let read_file_rev name =
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let ic = open_in name in
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let try_read () =
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try Some (input_line ic)
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with End_of_file -> None in
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let rec loop acc =
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match try_read () with
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| Some s -> loop (s::acc)
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| None -> close_in ic; acc in
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List.rev (loop [])
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let stepped_on_a_tree line pos =
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let width = String.length line in
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String.get line (pos mod width) = '#'
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let rec skiii count pos_x pos_y right down = function
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| [] -> count
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| h :: t -> if pos_y mod down <> 0 then skiii count pos_x (pos_y + 1) right down t
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else skiii (count + (if (stepped_on_a_tree h pos_x) then 1 else 0))
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(pos_x + right)
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(pos_y + 1)
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right down t
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let part1 l =
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skiii 0 0 0 3 1 l
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let part2 l =
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(skiii 0 0 0 1 1 l) *
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(skiii 0 0 0 3 1 l) *
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(skiii 0 0 0 5 1 l) *
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(skiii 0 0 0 7 1 l) *
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(skiii 0 0 0 1 2 l)
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let do_count filename = function
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| 1 -> read_file_rev filename |> part1
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| 2 -> read_file_rev filename |> part2
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let () =
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assert ((do_count "day3.test" 1) = 7)
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let () =
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print_endline (string_of_int (do_count "day3.input" 1))
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let () =
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assert ((do_count "day3.test" 2) = 336)
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let () =
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print_endline (string_of_int (do_count "day3.input" 2))
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