47 lines
1.5 KiB
OCaml
47 lines
1.5 KiB
OCaml
(** [matched_group_opt n s] returns [Some (Str.matched_group n s)] if the [n]th
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group matched, or [None] if the group did not match. *)
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let matched_group_opt n s = try Some (Str.matched_group n s) with _ -> None
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(** [find_nums s] returns the list of instructions given in [s]. *)
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let instrs_of_string s =
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let r =
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Str.regexp
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{|do()\|don't()\|mul(\([0-9][0-9]?[0-9]?\),\([0-9][0-9]?[0-9]?\))|}
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in
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let rec impl acc pos =
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try
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let _ = Str.search_forward r s pos in
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let p0 = Str.matched_group 0 s in
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let p1 = matched_group_opt 1 s in
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let p2 = matched_group_opt 2 s in
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impl
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((p0, Option.map int_of_string p1, Option.map int_of_string p2) :: acc)
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(Str.match_end ())
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with Not_found -> acc
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in
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List.rev (impl [] 0)
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let instrs_of_file fname =
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Aoc.strings_of_file fname |> List.map instrs_of_string |> List.concat
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(** [mac_opt acc a b] returns [acc + a' * b'] if [a = Some a'] and
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[b = Some b']. If either [a] or [b] are [None] then the result is [acc]. *)
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let mac_opt acc a b =
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acc + (Option.value a ~default:0 * Option.value b ~default:0)
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let day2403a = List.fold_left (fun acc (_, a, b) -> mac_opt acc a b) 0
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let day2403b lst =
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let rec impl acc enabled = function
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| [] -> acc
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| ("do()", _, _) :: t -> impl acc true t
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| ("don't()", _, _) :: t -> impl acc false t
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| (_, a, b) :: t ->
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if enabled then impl (mac_opt acc a b) true t else impl acc false t
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in
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impl 0 true lst
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let _ =
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Aoc.main instrs_of_file
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[ (string_of_int, day2403a); (string_of_int, day2403b) ]
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