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refactor day 8 a bit

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ryan committed 2023-10-01 13:12:36 -07:00
1 parent 7d6b43ba93
commit 239af2f93b
1 file changed
+38 -44
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src/day8.ml
+38 -44
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@@ -18,7 +18,7 @@ end = struct
let at grid point = let at grid point =
let x, y = to_tuple point in let x, y = to_tuple point in
let open Option in let open Option.Infix in
let* row = Array.get_safe grid y in let* row = Array.get_safe grid y in
Array.get_safe row x Array.get_safe row x
;; ;;
@@ -32,60 +32,54 @@ let parse_grid () =
Fun.(String.to_seq %> Seq.map (Char.to_string %> int_of_string) %> Seq.to_array) Fun.(String.to_seq %> Seq.map (Char.to_string %> int_of_string) %> Seq.to_array)
;; ;;
let rec find_taller_tree grid start_height start step = let solve grid fn =
let next = Vec2.(start + step) in let grid_h = Array.length grid in
match Vec2.at grid next with let grid_w = Array.length grid.(0) in
| Some height when height < start_height -> find_taller_tree grid start_height next step for y = 0 to grid_h - 1 do
| opt -> opt for x = 0 to grid_w - 1 do
let start = Vec2.of_tuple (x, y) in
fn start
done
done
;; ;;
let part1 () = let part1 () =
let grid = parse_grid () in let grid = parse_grid () in
let grid_h = Array.length grid in
let grid_w = Array.length grid.(0) in
let num_visible = ref 0 in let num_visible = ref 0 in
for y = 0 to grid_h - 1 do solve grid (fun start ->
for x = 0 to grid_w - 1 do let start_height = Option.get_exn_or "unreachable" @@ Vec2.at grid start in
let start = Vec2.of_tuple (x, y) in let rec walk_shorter_trees start step =
let height = Option.get_exn_or "unreachable" @@ Vec2.at grid start in let next = Vec2.(start + step) in
let visible = match Vec2.at grid next with
Vec2.directions | Some height when height < start_height -> walk_shorter_trees next step
|> List.map @@ find_taller_tree grid height start | opt -> opt
|> List.map Option.is_none in
|> List.reduce_exn ( || ) let visible =
in Vec2.directions
if visible then incr num_visible |> List.map @@ walk_shorter_trees start
done |> List.map Option.is_none
done; |> List.reduce_exn ( || )
in
if visible then incr num_visible);
!num_visible !num_visible
;; ;;
let rec trees_in_view grid start start_height in_view step =
let next = Vec2.(start + step) in
match Vec2.at grid next with
| Some height when height < start_height ->
trees_in_view grid next start_height (in_view + 1) step
| Some _ -> in_view + 1
| None -> in_view
;;
let part2 () = let part2 () =
let grid = parse_grid () in let grid = parse_grid () in
let grid_h = Array.length grid in
let grid_w = Array.length grid.(0) in
let best_score = ref 0 in let best_score = ref 0 in
for y = 0 to grid_h - 1 do solve grid (fun start ->
for x = 0 to grid_w - 1 do let start_height = Option.get_exn_or "unreachable" @@ Vec2.at grid start in
let start = Vec2.of_tuple (x, y) in let rec trees_in_view start in_view step =
let height = Option.get_exn_or "unreachable" @@ Vec2.at grid start in let next = Vec2.(start + step) in
let score = match Vec2.at grid next with
Vec2.directions | Some height when height < start_height -> trees_in_view next (in_view + 1) step
|> List.map @@ trees_in_view grid start height 0 | Some _ -> in_view + 1
|> List.reduce_exn ( * ) | None -> in_view
in in
if score > !best_score then best_score := score let score =
done Vec2.directions |> List.map @@ trees_in_view start 0 |> List.reduce_exn ( * )
done; in
if score > !best_score then best_score := score);
!best_score !best_score
;; ;;