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