Add 2025 day 25.

We want to change Aoc.main to take a single printer parameter to
simplify the run process.

bin/day2417.ml

@@ -129,7 +129,8 @@ let rec execute_until_halted vm =
   | false -> execute_until_halted (execute_insn vm)
 
 (** [string_of_ouput vm] gives the output of [vm]. *)
-let string_of_output vm =
+let part1 vm =
+  let vm = execute_until_halted vm in
   List.rev vm.out |> List.map string_of_int |> String.concat ","
 
 (** [scan_digit acc ip vm] updates the acc for A so that the output of running
@@ -159,8 +160,8 @@ let scan_all vm =
   impl 0 (Array.length vm.code - 1)
 
 (** [string_of_a vm] returns the A register of [vm]. *)
-let string_of_a vm = string_of_int vm.a
+let part2 vm =
+  let vm = scan_all vm in
+  string_of_int vm.a
 
-let _ =
-  Aoc.main vm_of_file
-    [ (string_of_output, execute_until_halted); (string_of_a, scan_all) ]
+let _ = Aoc.main vm_of_file [ (Fun.id, part1); (Fun.id, part2) ]

bin/day2418.ml

@@ -104,12 +104,12 @@ let find_route_length count grid =
 let part1 count rocks =
   match find_route_length count rocks with
   | None -> failwith "part1"
-  | Some (cost, _) -> cost
+  | Some (cost, _) -> string_of_int cost
 
 (** [part2 start_count grid] returns the location of the first rock to fall into
     [grid] which makes it impossible to get from the top-left to bottom-right.
 *)
-let part2 start_count grid =
+let part2 width start_count grid =
   (* Implementation notes:
   
      We do this by binary search in impl.  The left_count is a known count of
@@ -137,16 +137,11 @@ let part2 start_count grid =
   let count = impl start_count (1 + count_rocks 0 0) in
   match Array.find_index (( = ) (count - 1)) grid.grid with
   | None -> failwith "part2"
-  | Some idx -> idx
-
-(** [string_of_idx width idx] prints the (x, y) location for a given index in a
-    grid. *)
-let string_of_idx width idx =
-  Printf.sprintf "%d,%d" (idx mod width) (idx / width)
+  | Some idx -> Printf.sprintf "%d,%d" (idx mod width) (idx / width)
 
 (** Width of grid *)
 let width = 71
 
 let _ =
   Aoc.main (grid_of_file width)
-    [ (string_of_int, part1 1024); (string_of_idx width, part2 1024) ]
+    [ (Fun.id, part1 1024); (Fun.id, part2 width 1024) ]

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) ]

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))