1 files changed, 57 insertions, 0 deletions
diff --git a/lib/day12.ml b/lib/day12.ml
new file mode 100644
index 0000000..bb687be
--- /dev/null
+++ b/lib/day12.ml
@@ -0,0 +1,57 @@
+(*
+ * SPDX-FileCopyrightText: Copyright 2025 Alexandre Jesus <https://adbjesus.com>
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *)
+
+type puzzle = { n : int; m : int; q : int list }
+type shape = { n : int; m : int; g : bool array array }
+
+let parse ch =
+  let parse_puzzle s =
+    let d = String.trim s |> String.split_on_char ':' in
+    match d with
+    | sz :: (q :: []) ->
+       let n, m = Scanf.sscanf sz "%dx%d" (fun n m -> (n, m)) in
+       let q = String.trim q |> String.split_on_char ' ' |> List.map int_of_string in
+       { n; m;  q}
+    | _ -> failwith ("Invalid puzzle: "^s)
+  in
+  let rec parse_shape l acc =
+    let make_res tl =
+      let g = List.rev acc |> Array.of_list in
+      let n = Array.length g in
+      let m = Array.length g.(0) in
+      (tl, { n; m; g })
+    in
+    match l with
+    | [] -> make_res []
+    | "" :: tl -> make_res tl
+    | line :: tl ->
+       let gl = String.to_seq line |> Seq.map (fun c -> c = '#') |> Array.of_seq in
+       parse_shape tl (gl :: acc)
+  in
+  let rec parse_all shapes puzzles l =
+    match l with
+    | [] -> (List.rev shapes, List.rev puzzles)
+    | "" :: tl -> parse_all shapes puzzles tl
+    | s :: tl ->
+       match Scanf.sscanf_opt s "%d:" (fun _ -> parse_shape tl []) with
+       | Some (l, shape) -> parse_all (shape :: shapes) puzzles l
+       | None -> parse_all shapes ((parse_puzzle s) :: puzzles) tl
+  in
+  In_channel.input_lines ch
+  |> parse_all [] []
+
+let solve_naive shapes puzzle =
+  (* This is NOT a solution to the general problem, but is enough for the given input *)
+  List.map2 (fun s c -> s.n * s.m * c) shapes puzzle.q
+  |> List.fold_left ( + ) 0
+  |> fun a -> if a <= puzzle.n * puzzle.m then 1 else 0
+  
+let part1 ch =
+  let shapes, puzzles = parse ch in
+  List.map (solve_naive shapes) puzzles
+  |> List.fold_left ( + ) 0
+  |> Printf.printf "%d\n"
+