Clean up

lib/year2023/day11.ml

@@ -2,27 +2,23 @@ module Coord = struct
   type t = int * int [@@deriving equal, compare, sexp]
 end
 
-module CoordPair = struct
-  type t = Coord.t * Coord.t [@@deriving equal, compare, sexp]
-end
-
 module IntMap = Map.Make (Int)
 module CoordMap = Map.Make (Coord)
-module CoordPairSet = Set.Make (CoordPair)
 
 let parse input = input |> String.split_lines |> List.map ~f:String.to_list
 
 let expand amount galaxy =
+  let open Z in
   let x_counts =
     galaxy
     |> List.transpose_exn
     |> List.mapi ~f:(fun i line ->
-      i, if List.for_all line ~f:(Char.equal '.') then amount else 1)
+      i, if List.for_all line ~f:(Char.equal '.') then ~$amount else ~$1)
   in
   let y_counts =
     galaxy
     |> List.mapi ~f:(fun i line ->
-      i, if List.for_all line ~f:(Char.equal '.') then amount else 1)
+      i, if List.for_all line ~f:(Char.equal '.') then ~$amount else ~$1)
   in
   IntMap.of_alist_exn x_counts, IntMap.of_alist_exn y_counts
 ;;
@@ -34,29 +30,22 @@ let to_grid galaxy =
 ;;
 
 let pairs grid =
-  let stars = grid |> Map.filter ~f:(Char.equal '#') |> Map.keys in
-  stars
-  |> List.concat_map ~f:(fun a ->
-    List.filter_map stars ~f:(fun b ->
-      if Coord.equal a b
-      then None
-      else if Coord.compare a b < 0
-      then Some (a, b)
-      else Some (b, a)))
-  |> CoordPairSet.of_list
+  let rec all_pairs = function
+    | a :: rest -> List.map rest ~f:(fun b -> a, b) @ all_pairs rest
+    | [] -> []
+  in
+  grid |> Map.filter ~f:(Char.equal '#') |> Map.keys |> all_pairs
 ;;
 
 let range a b = if a < b then List.range a b else List.range b a
 
 let distance x_counts y_counts ((x1, y1), (x2, y2)) =
   let open Z in
   let x_dist =
-    range x1 x2
-    |> List.fold ~init:Z.zero ~f:(fun sum x -> ~$(Map.find_exn x_counts x) + sum)
+    range x1 x2 |> List.fold ~init:~$0 ~f:(fun sum x -> Map.find_exn x_counts x + sum)
   in
   let y_dist =
-    range y1 y2
-    |> List.fold ~init:Z.zero ~f:(fun sum y -> ~$(Map.find_exn y_counts y) + sum)
+    range y1 y2 |> List.fold ~init:~$0 ~f:(fun sum y -> Map.find_exn y_counts y + sum)
   in
   x_dist + y_dist
 ;;
@@ -67,7 +56,6 @@ let solve amount input =
   galaxy
   |> to_grid
   |> pairs
-  |> Set.to_list
   |> List.map ~f:(distance x_counts y_counts)
   |> List.fold ~init:Z.zero ~f:Z.add
   |> Z.to_string