mgrettondann/ocaml-aoc
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Update to use Aoc.pow10 and Aoc.digits10.

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Matthew Gretton-Dann
2024-12-11 09:17:12 +00:00
parent 2159a5fc5e
commit fcc4341237
1 changed files with 1 additions and 15 deletions
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bin/day2407.ml
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@@ -1,20 +1,6 @@
let ints_of_file fname =
Aoc.strings_of_file fname |> List.map (Aoc.ints_of_string ~sep:"[: ]+")
(** [log10i i] returns the integer part of [log10 i]. [i] must be greater than
zero. *)
let log10i i =
let rec impl acc = function 0 -> acc | x -> impl (acc + 1) (x / 10) in
assert (i > 0);
impl ~-1 i
(** [pow10 n] returns [10] raised to the [n]th power. [n] must be non-negative.
*)
let pow10 n =
let rec impl acc = function 0 -> acc | x -> impl (acc * 10) (x - 1) in
assert (n >= 0);
impl 1 n
(** [check_add tgt v] Check to see if [X + v = tgt] is a valid operation. If not
returns [None] otherwise returns [Some X]. *)
let check_add tgt v = if v > tgt then None else Some (tgt - v)
@@ -26,7 +12,7 @@ let check_mul tgt v = if tgt mod v = 0 then Some (tgt / v) else None
(** [check_cat tgt v] Check to see if [X || v = tgt] is a valid operation. If
not returns [None] otherwise returns [Some X]. *)
let check_cat tgt v =
let p = pow10 (1 + log10i v) in
let p = Aoc.pow10 (Aoc.digits10 v) in
if tgt mod p = v then Some (tgt / p) else None
(** [is_valid_target tgt nums ops] returns [true] if we can reach [tgt] from