From aea97249141e802fbe9190edbdd1b1f0742b7c63 Mon Sep 17 00:00:00 2001
From: Matthew Gretton-Dann <matt@gretton-dann.org.uk>
Date: Wed, 25 Dec 2024 12:34:08 +0000
Subject: [PATCH] Add 2025 day 25.

---
 bin/day2425.ml | 34 ++++++++++++++++++++++++++++++++++
 bin/dune       |  6 ++++--
 2 files changed, 38 insertions(+), 2 deletions(-)
 create mode 100644 bin/day2425.ml

diff --git a/bin/day2425.ml b/bin/day2425.ml
new file mode 100644
index 0000000..7804726
--- /dev/null
+++ b/bin/day2425.ml
@@ -0,0 +1,34 @@
+let pin_count = 5
+let height = 7
+
+let read_lock_or_key lst =
+  let result = Array.make pin_count 0 in
+  let add_node i c = if c = '#' then result.(i) <- result.(i) + 1 in
+  List.iter (String.iteri add_node) lst;
+  result |> Array.to_list
+
+let locks_and_keys_of_list =
+  let rec impl locks keys = function
+    | [] -> (locks, keys)
+    | "" :: t -> impl locks keys t
+    | a :: b :: c :: d :: e :: f :: g :: t ->
+        let h = read_lock_or_key [ a; b; c; d; e; f; g ] in
+        if a = String.make pin_count '#' then impl locks (h :: keys) t
+        else impl (h :: locks) keys t
+    | _ -> failwith "locks_and_keys_of_list"
+  in
+  impl [] []
+
+let locks_and_keys_of_file fname =
+  Aoc.strings_of_file fname |> locks_and_keys_of_list
+
+let lock_key_fit lock key =
+  List.map2 ( + ) lock key |> List.for_all (( >= ) height)
+
+let count_keys keys lock = List.filter (lock_key_fit lock) keys |> List.length
+
+let count_locks_and_keys (locks, keys) =
+  List.map (count_keys keys) locks |> List.fold_left ( + ) 0
+
+let _ =
+  Aoc.main locks_and_keys_of_file [ (string_of_int, count_locks_and_keys) ]
diff --git a/bin/dune b/bin/dune
index 23c4cc1..9304fc6 100644
--- a/bin/dune
+++ b/bin/dune
@@ -23,7 +23,8 @@
   day2421
   day2422
   day2423
-  day2424)
+  day2424
+  day2425)
  (names
   day2401
   day2402
@@ -48,5 +49,6 @@
   day2421
   day2422
   day2423
-  day2424)
+  day2424
+  day2425)
  (libraries str aoc))