46 lines
1.4 KiB
OCaml
46 lines
1.4 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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loop []
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let count_good_passwords f l =
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let is_conforming f entry =
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let [term; pass] = String.split_on_char ':' entry in
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let [rep; letter] = String.split_on_char ' ' term in
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let [minr; maxr] = List.map int_of_string (String.split_on_char '-' rep) in
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f pass minr maxr letter.[0] in
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List.map (is_conforming f) l
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|> List.map (fun b -> if b then 1 else 0)
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|> List.fold_left (+) 0
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let part1_f pass minr maxr letter =
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let count = List.length (String.split_on_char letter pass) - 1 in
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minr <= count && count <= maxr
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let part2_f pass first second letter =
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let position_matches pass pos letter =
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match String.get pass pos with
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| c -> c = letter
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| _ -> false in
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(position_matches pass first letter) <> (position_matches pass second letter)
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let do_count filename = function
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| 1 -> read_file_rev filename |> count_good_passwords part1_f
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| 2 -> read_file_rev filename |> count_good_passwords part2_f
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let () =
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print_endline (string_of_int (do_count "day2.input" 1))
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let () =
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print_endline (string_of_int (do_count "day2.input" 2))
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