Move to use Aoc.Grid

bin/day2406.ml

@@ -1,50 +1,26 @@
-type map = { map : string; width : int; height : int }
-(** [map] represents a map with layout [map] and a [width] and [height].
-    [map.map] is a string of length [width * height] with the [i]th character
-    describing the position [(i mod map.width, i / map.width)]. *)
-
 (** [find_start strs] returns the location [(x, y)] of the starting position. *)
 let find_start map =
-  match String.index_from_opt map.map 0 '^' with
-  | Some i -> (i mod map.width, i / map.width)
+  match Aoc.Grid.idx_from_opt map 0 '^' with
+  | Some i -> Aoc.Grid.pos_of_idx map i
   | None -> failwith "find_start"
 
-(** [map_of_strings strs] returns the map generated from the input map described
-    by the list of strings [strs] *)
-let map_of_strings strs =
-  let width = String.length (List.hd strs) in
-  let map = List.fold_left String.cat "" strs in
-  let height = String.length map / width in
-  { map; width; height }
-
 (** [read_file fname] reads the input map from [fname]. It returns a
     [(map, pos, vel)] tuple, consisting of the obsticle map, initial position,
     and initial velocity. *)
 let read_file fname =
-  let lst = Aoc.strings_of_file fname in
-  let map = map_of_strings lst in
+  let map = Aoc.Grid.of_file fname in
   let pos = find_start map in
   (map, pos, (0, -1))
 
-(** [is_valid_pos map pos] returns true if the position [pos] is valid for the
-    map [map]. *)
-let is_valid_pos map (x, y) =
-  if y < 0 || y >= map.height then false
-  else if x < 0 || x >= map.width then false
-  else true
-
 (** [is_block map pos] returns [true] iff the location [pos] is a blockages in
     [map]. *)
-let is_block map (x, y) =
-  if is_valid_pos map (x, y) then map.map.[x + (y * map.width)] = '#' else false
+let is_block map pos =
+  if Aoc.Grid.pos_is_valid map pos then Aoc.Grid.get_by_pos map pos = '#'
+  else false
 
 (** [insert_block map pos] inserts a blockage at [pos] into [map] and returns
     the new map. *)
-let insert_block map (x, y) =
-  let idx = x + (y * map.width) in
-  let start = String.sub map.map 0 idx in
-  let e = String.sub map.map (idx + 1) (String.length map.map - idx - 1) in
-  { map with map = start ^ "#" ^ e }
+let insert_block map pos = Aoc.Grid.update_pos map pos '#'
 
 (** [move map (pos, vel)] moves [pos] one step forward on the [map]. [vel] gives
     the movement vector. If the movement will cause an obstacle to be hit then
@@ -60,7 +36,8 @@ let rec move map ((x, y), (dx, dy)) =
     off one of the sides. *)
 let walk_map map (pos, vel) =
   let rec impl acc (pos, vel) =
-    if is_valid_pos map pos then impl (pos :: acc) (move map (pos, vel))
+    if Aoc.Grid.pos_is_valid map pos then
+      impl (pos :: acc) (move map (pos, vel))
     else acc
   in
   impl [] (pos, vel)
@@ -75,7 +52,7 @@ let has_cycles map start =
   let rec impl agent1 ((pos', _) as agent2) =
     (* Only need to check pos' for validity because if pos is not valid then
        pos' must also be invalid, and have been invalid before this. *)
-    if not (is_valid_pos map pos') then false
+    if not (Aoc.Grid.pos_is_valid map pos') then false
     else if agent1 = agent2 then true
     else impl (move map agent1) (move map (move map agent2))
   in