3 files changed, 113 insertions, 29 deletions
diff --git a/2025/ocaml/lib/application/d02p01.ml b/2025/ocaml/lib/application/d02p01.ml
index c4eebbe..2d833be 100644
--- a/2025/ocaml/lib/application/d02p01.ml
+++ b/2025/ocaml/lib/application/d02p01.ml
@@ -1,31 +1,46 @@
-let pp_range range =
-  Logs.app (fun m -> m "range=%s" range) ;
-  range
-
-let pp_tuple tuple =
-  let l, r = tuple in
-  Logs.app (fun m -> m "(left=%s, right=%s)" l r) ;
-  tuple
-
-(** [input_to_ranges input] is a list of strings that have been split on ','.
-    Requires: [input] to be a string in the format "12-34,56-78,90-100" *)
-let input_to_ranges input =
-  input |> String.split_on_char ','
-  |> List.filter (fun range -> range <> "")
-  |> List.map pp_range
-
-let list_to_tuple = function
-  | [l; r] ->
-      (l, r)
-  | _ ->
-      failwith "list cannot convert to tuple"
-
-let ranges_to_tuples ranges =
-  ranges
-  |> List.map (fun range ->
-      let sides = String.split_on_char '-' range in
-      list_to_tuple sides |> pp_tuple )
+open Domain.D02p01
+
+(** [input_to_lines input] is a list of strings that have been split on ','.
+    Example: [input_to_lines "12-34,56-78,90-100"] becomes the list \[ "12-34"; "56-78"; "90-100" \].
+    Requires: [input] to be a string in the format "12-34,56-78,90-100". *)
+let input_to_lines input = input |> String.trim |> String.split_on_char ','
+
+let pp_lines = List.iter (fun l -> Logs.debug (fun m -> m "line=%s" l))
+
+(** [lines_to_ranges line] is a list of [Range]s found on [line]. *)
+let lines_to_ranges =
+  List.map (fun line ->
+      Scanf.sscanf line "%d-%d" (fun id1 id2 -> Range.create (id1, id2)) )
+
+let pp_ranges = List.iter (fun r -> Logs.debug (fun m -> m "%s" (Range.pp r)))
+
+(** [collect_all ranges] is an unsorted list of [ID]s within the [ranges] (inclusive). *)
+let collect_all = List.concat_map (fun range -> Range.collect range)
+
+let pp_collection = List.iter (fun c -> Logs.debug (fun m -> m "%s" (ID.pp c)))
+
+(** [rules] is a list of rules that [ID]s must pass to be considered invalid. *)
+let rules =
+  [ (fun id -> String.length (ID.to_string id) mod 2 = 0)
+  ; (fun id ->
+      let id' = ID.to_string id in
+      let id_len = String.length id' in
+      let left = String.sub id' 0 (id_len / 2) in
+      let right = String.sub id' (id_len / 2) (id_len / 2) in
+      String.equal left right ) ]
+
+(** [is_invalid id] is [true] for an [id] that passes all of the rules and is considered invalid. *)
+let is_invalid = ID.validate rules
+
+(** [passthrough_with_logs logger lst] is [lst] with the side-effects caused by calling [logger] on [lst]. *)
+let passthrough_with_logs logger lst = logger lst ; lst
 
 let solve input () =
-  let _ = input |> input_to_ranges |> ranges_to_tuples in
-  0
+  input |> input_to_lines
+  |> passthrough_with_logs pp_lines
+  |> lines_to_ranges
+  |> passthrough_with_logs pp_ranges
+  |> collect_all
+  |> passthrough_with_logs pp_collection
+  |> List.filter is_invalid
+  |> List.fold_left (fun acc id -> acc + ID.to_int id) 0
diff --git a/2025/ocaml/lib/domain/d02p01.ml b/2025/ocaml/lib/domain/d02p01.ml
new file mode 100644
index 0000000..725d4b1
--- /dev/null
+++ b/2025/ocaml/lib/domain/d02p01.ml
@@ -0,0 +1,33 @@
+module ID = struct
+  (** *)
+  type t = int
+
+  let create num = num
+
+  let validate rules id = List.fold_left (fun acc r -> acc && r id) true rules
+
+  let incr = ( + ) 1
+
+  let to_int id = id
+
+  let to_string = string_of_int
+
+  let pp id = "ID=" ^ string_of_int id
+end
+
+module Range = struct
+  type t = ID.t * ID.t
+
+  let create (id1, id2) = (ID.create id1, ID.create id2)
+
+  let rec collect range = collect_range_aux [] range
+
+  and collect_range_aux lst (id1, id2) =
+    match id1 <= id2 with
+    | false ->
+        lst
+    | true ->
+        collect_range_aux (id1 :: lst) (ID.incr id1, id2)
+
+  let pp (id1, id2) = "(L" ^ ID.pp id1 ^ ", R" ^ ID.pp id2 ^ ")"
+end
diff --git a/2025/ocaml/lib/domain/d02p01.mli b/2025/ocaml/lib/domain/d02p01.mli
new file mode 100644
index 0000000..55665fe
--- /dev/null
+++ b/2025/ocaml/lib/domain/d02p01.mli
@@ -0,0 +1,36 @@
+module ID : sig
+  (** [t] is a ID within a range *)
+  type t
+
+  val create : int -> t
+  (** [create num] is an ID [t] *)
+
+  val validate : (t -> bool) list -> t -> bool
+  (** [validate rules id] is [true] if the [id] passes all rule checks *)
+
+  val incr : t -> t
+  (** [incr id] is the next [id] in the sequence *)
+
+  val to_int : t -> int
+  (** [to_int id] is an integer representation of [id] *)
+
+  val to_string : t -> string
+  (** [to_string id] is an string representation of [id] *)
+
+  val pp : t -> string
+  (** [pp id] is a pretty string representing [id] *)
+end
+
+module Range : sig
+  (** [t] is a range of values *)
+  type t
+
+  val create : int * int -> t
+  (** [create (s, e)] is a range starting at [s] and ending at [e]. *)
+
+  val collect : t -> ID.t list
+  (** [collect r] is a list containing all elements within the range (inclusive). *)
+
+  val pp : t -> string
+  (** [pp r] is a pretty string representing [r] *)
+end