From 9ed30f54f5d73fcdc9a56613baed28c53659aba5 Mon Sep 17 00:00:00 2001
From: DJ O'Leary <dijitol@proton.me>
Date: Sat, 6 Dec 2025 21:22:31 +0100
Subject: feat(2025d3p1): partial solution, getting the wrong answer

Manually did entire real input and codified into tests but even sum of manual
answer is wrong. Code fails for some lines of real input and these
failing lines have been reduced into regression tests.

work-in-progress: true
---
 2025/ocaml/lib/domain/d03p01.ml | 99 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 99 insertions(+)

(limited to '2025/ocaml/lib/domain/d03p01.ml')

diff --git a/2025/ocaml/lib/domain/d03p01.ml b/2025/ocaml/lib/domain/d03p01.ml
index e69de29..7f56bdc 100644
--- a/2025/ocaml/lib/domain/d03p01.ml
+++ b/2025/ocaml/lib/domain/d03p01.ml
@@ -0,0 +1,99 @@
+module Battery : sig
+  type t
+
+  val of_int : int -> t
+
+  val to_int : t -> int
+
+  val to_string : t -> string
+
+  val compare : t -> t -> int
+
+  val pp : t -> string
+end = struct
+  type t = int
+
+  let of_int i = i
+
+  let to_int b = b
+
+  let to_string = string_of_int
+
+  let compare = Int.compare
+
+  let pp = string_of_int
+end
+
+module BatteryBank : sig
+  type t
+
+  val highest_joltage : t -> int
+
+  val of_string : string -> t
+
+  val of_list : Battery.t list -> t
+
+  val to_list : t -> Battery.t list
+
+  val pp : t -> string
+end = struct
+  type t = Battery.t list
+
+  let rec highest_joltage bb =
+    match highest_joltage_aux (None, None) bb with
+    | None, None ->
+        0
+    | Some x, Some y ->
+        int_of_string (Battery.to_string x ^ Battery.to_string y)
+    | _ ->
+        failwith "this branch should be impossible"
+
+  and highest_joltage_aux acc = function
+    | [] ->
+        acc
+    | h :: t ->
+        highest_joltage_aux
+          ( match acc with
+          | None, None ->
+              (Some h, None)
+          | Some first, None ->
+              (Some first, Some h)
+          | Some first, Some second ->
+              swap_if_higher first second h (List.length t = 0)
+          | _ ->
+              failwith "this branch should be impossible" )
+          t
+
+  and swap_if_higher first second considering is_end =
+    let c_gt_f = Battery.compare considering first = 1 in
+    let c_gt_s = Battery.compare considering second = 1 in
+    let f_gt_s = Battery.compare first second = 1 in
+    if c_gt_f && c_gt_s && f_gt_s then
+      if is_end then (Some first, Some considering) else (Some considering, None)
+    else if (not c_gt_f) && c_gt_s && f_gt_s then (Some first, Some considering)
+    else if c_gt_f && c_gt_s && not f_gt_s then
+      if is_end then (Some second, Some considering)
+      else (Some considering, None)
+    else if (not c_gt_f) && (not c_gt_s) && f_gt_s then (Some first, Some second)
+    else if c_gt_f && (not c_gt_s) && not f_gt_s then
+      (Some second, Some considering)
+    else (Some first, Some second)
+
+  let of_string s =
+    s |> String.to_seq
+    |> Seq.map (fun c -> Char.escaped c |> int_of_string |> Battery.of_int)
+    |> List.of_seq
+
+  let of_list lst = lst
+
+  let to_list bb = bb
+
+  let pp bb =
+    "[ "
+    ^ ( bb |> List.map Battery.pp
+      |> List.fold_left
+           (fun acc b ->
+             if acc = "" then b ^ ";" else Printf.sprintf "%s %s;" acc b )
+           "" )
+    ^ " ]"
+end
-- 
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