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refactor day 8 a bit

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This commit is contained in:
ryan 2023-10-01 13:12:36 -07:00
parent 7d6b43ba93
commit 239af2f93b
1 changed files with 38 additions and 44 deletions
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82
src/day8.ml
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@ -18,7 +18,7 @@ end = struct
let at grid point =
let x, y = to_tuple point in
let open Option in
let open Option.Infix in
let* row = Array.get_safe grid y in
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)
;;
let rec find_taller_tree grid start_height start step =
let next = Vec2.(start + step) in
match Vec2.at grid next with
| Some height when height < start_height -> find_taller_tree grid start_height next step
| opt -> opt
let solve grid fn =
let grid_h = Array.length grid in
let grid_w = Array.length grid.(0) in
for y = 0 to grid_h - 1 do
for x = 0 to grid_w - 1 do
let start = Vec2.of_tuple (x, y) in
fn start
done
done
;;
let part1 () =
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
for y = 0 to grid_h - 1 do
for x = 0 to grid_w - 1 do
let start = Vec2.of_tuple (x, y) in
let height = Option.get_exn_or "unreachable" @@ Vec2.at grid start in
let visible =
Vec2.directions
|> List.map @@ find_taller_tree grid height start
|> List.map Option.is_none
|> List.reduce_exn ( || )
in
if visible then incr num_visible
done
done;
solve grid (fun start ->
let start_height = Option.get_exn_or "unreachable" @@ Vec2.at grid start in
let rec walk_shorter_trees start step =
let next = Vec2.(start + step) in
match Vec2.at grid next with
| Some height when height < start_height -> walk_shorter_trees next step
| opt -> opt
in
let visible =
Vec2.directions
|> List.map @@ walk_shorter_trees start
|> List.map Option.is_none
|> List.reduce_exn ( || )
in
if visible then incr 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 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
for y = 0 to grid_h - 1 do
for x = 0 to grid_w - 1 do
let start = Vec2.of_tuple (x, y) in
let height = Option.get_exn_or "unreachable" @@ Vec2.at grid start in
let score =
Vec2.directions
|> List.map @@ trees_in_view grid start height 0
|> List.reduce_exn ( * )
in
if score > !best_score then best_score := score
done
done;
solve grid (fun start ->
let start_height = Option.get_exn_or "unreachable" @@ Vec2.at grid start in
let rec trees_in_view start in_view step =
let next = Vec2.(start + step) in
match Vec2.at grid next with
| Some height when height < start_height -> trees_in_view next (in_view + 1) step
| Some _ -> in_view + 1
| None -> in_view
in
let score =
Vec2.directions |> List.map @@ trees_in_view start 0 |> List.reduce_exn ( * )
in
if score > !best_score then best_score := score);
!best_score
;;