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tjdevries/day_8_1.ml

Created December 8, 2022 19:41
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day_8_1.ml
module CoordSet = Set.Make (struct
type t = int * int
let compare = Stdlib.compare
end)
let part_1 input =
let size = List.hd input |> String.length in
let matrix_n = Array.init size (fun _ -> Array.make size 0) in
let transform_n row col = row, col in
let matrix_s = Array.init size (fun _ -> Array.make size 0) in
let transform_s row col = size - 1 - row, col in
let matrix_e = Array.init size (fun _ -> Array.make size 0) in
let transform_e row col = col, row in
let matrix_w = Array.init size (fun _ -> Array.make size 0) in
let transform_w row col = col, size - 1 - row in
let row_iter row col ch =
(* Something *)
let value = int_of_char ch - 48 in
matrix_n.(row).(col) <- value;
matrix_s.(size - 1 - row).(col) <- value;
matrix_e.(col).(row) <- value;
matrix_w.(size - 1 - col).(row) <- value
in
List.iteri (fun row line -> String.iteri (row_iter row) line) input;
let coords = ref CoordSet.empty in
let update_coords coords matrix transform =
let maxs = Array.make size (-1) in
let row_iter row col height =
let max_height = maxs.(col) in
if height > max_height then (
(* Bigger height, so track and update *)
coords := CoordSet.add (transform row col) !coords;
maxs.(col) <- height
)
in
Array.iteri (fun rowi row -> Array.iteri (row_iter rowi) row) matrix
in
update_coords coords matrix_n transform_n;
update_coords coords matrix_s transform_s;
update_coords coords matrix_e transform_e;
update_coords coords matrix_w transform_w;
Format.printf "Count: %d\n" (CoordSet.cardinal !coords)
;;
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