Update to use Aoc.pow10 and Aoc.digits10.

bin/day2407.ml

@@ -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