blob: 75b123646a71bc4367a96d5a146e5a659f3fcb2a (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
|
open Domain
let err_empty_input = "input is empty"
let rec count_accessible_rolls matrix =
let count_paper lst = List.length @@ List.filter (fun c -> c = "@") lst in
let accessible_rolls_of_paper = ref [] in
let no_change = ref false in
while not !no_change do
let accessible_rolls_of_paper' = !accessible_rolls_of_paper in
count_accessible_rolls_aux matrix count_paper accessible_rolls_of_paper ;
if
List.length accessible_rolls_of_paper'
= List.length !accessible_rolls_of_paper
then no_change := true
done ;
List.length !accessible_rolls_of_paper
and count_accessible_rolls_aux matrix count_paper accessible_rolls_of_paper =
for y = 0 to Array.length matrix - 1 do
for x = 0 to Array.length matrix.(y) - 1 do
if matrix.(y).(x) = "." then ()
else
let neighbour_coords = Matrix.M.get_valid_neighbours matrix x y in
let neighbours =
List.map (fun (nx, ny) -> Matrix.M.get matrix nx ny) neighbour_coords
in
let paper_count = count_paper neighbours in
let is_accessible = paper_count < 4 in
if is_accessible then
accessible_rolls_of_paper := (x, y) :: !accessible_rolls_of_paper ;
print_iteration_debug_msg x y neighbour_coords neighbours paper_count
is_accessible
done
done ;
List.iter
(fun (x', y') -> Matrix.M.set matrix x' y' ".")
!accessible_rolls_of_paper
and print_iteration_debug_msg x y neighbour_coords neighbours paper_count
is_accessible =
Logs.debug (fun m ->
m
"coords=(%d,%d) neighbour_coords=[%s] neighbours=[%s] paper=%d \
is_accessible=%B"
x y
(List.fold_left
(fun acc (x, y) ->
if acc = "" then
" (" ^ string_of_int x ^ "," ^ string_of_int y ^ "); "
else acc ^ "(" ^ string_of_int x ^ "," ^ string_of_int y ^ "); " )
"" neighbour_coords )
(List.fold_left
(fun acc neighbour ->
if acc = "" then " " ^ neighbour ^ "; " else acc ^ neighbour ^ "; " )
"" neighbours )
paper_count is_accessible )
let solve input () =
if input = "" then Error err_empty_input
else
let matrix = Matrix.M.of_string input in
let accessible_rolls_of_paper = count_accessible_rolls matrix in
Ok accessible_rolls_of_paper
|
