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

2 files changed, 37 insertions, 1 deletions

diff --git a/2025/ocaml/lib/application/d03p01.ml b/2025/ocaml/lib/application/d03p01.ml
index b63679e..8e9c32c 100644
--- a/2025/ocaml/lib/application/d03p01.ml
+++ b/2025/ocaml/lib/application/d03p01.ml
@@ -15,6 +15,40 @@
    5. Cast to int
 
    Sum the result of each line
+
+   Tried: 17024 (hint: too low) - original
+   Tried: 17061 (hint: too low) - fixed second digit promotion - "343411" would give 41 instead of 44
+   Tried: 17081 (no hint given) - fixed second last digit promotion - "789" would give 79 insted of 89
+   Tried: 17091 (no hint given) - no change but found diff of 10 in failing test case
+   Tried: 17090 (no hint given) - no change but realised failing test case actually had a diff of 9 not 10 (have 56, want 65)
+   Tried: 17099 (no hint given) - no change but found additional failing test case (have 67, want 76)
+
+   Upper bound: 200 * 99 = 19800
  *)
 
-let solve _ () = failwith "not started"
+open Domain.D03p01
+
+let to_lines s =
+  s |> String.split_on_char '\n' |> List.map String.trim
+  |> List.filter (fun l -> l <> "")
+
+let solve input () =
+  input |> to_lines |> List.to_seq
+  |> Seq.map BatteryBank.of_string
+  |> Seq.mapi (fun idx bb ->
+      let joltage = BatteryBank.highest_joltage bb in
+      Logs.debug (fun m ->
+          m "%d line=%s highest_joltage=%d" (idx + 1) (BatteryBank.pp bb)
+            joltage ) ;
+      joltage )
+  |> Seq.fold_left ( + ) 0
+
+let print_occurring_digits input () =
+  input |> to_lines |> List.to_seq
+  |> Seq.map BatteryBank.of_string
+  |> Seq.map BatteryBank.to_list
+  |> Seq.map (List.sort_uniq Battery.compare)
+  |> Seq.map BatteryBank.of_list
+  |> Seq.iteri (fun idx bb ->
+      Logs.debug (fun m -> m "%d %s" (idx + 1) (BatteryBank.pp bb)) ) ;
+  -1
diff --git a/2025/ocaml/lib/application/d03p01.mli b/2025/ocaml/lib/application/d03p01.mli
index 85f7e78..d875e40 100644
--- a/2025/ocaml/lib/application/d03p01.mli
+++ b/2025/ocaml/lib/application/d03p01.mli
@@ -2,3 +2,5 @@ val solve : string -> unit -> int
 (** [solve input ()] is the solution for the first part of the third day of advent of code 2025 for [input].
     The solution for an empty input is 0.
     Requires: [input] to be a string. *)
+
+val print_occurring_digits : string -> unit -> int