71 lines
1.9 KiB
OCaml
71 lines
1.9 KiB
OCaml
let search_string big little =
|
|
let re = Str.regexp_string little in
|
|
let rec impl acc pos =
|
|
try
|
|
let _ = Str.search_forward re big pos in
|
|
impl (acc + 1) (Str.match_end ())
|
|
with Not_found -> acc
|
|
in
|
|
impl 0 0
|
|
|
|
let is_inbounds sa (x, y) =
|
|
y >= 0 && y < Array.length sa && x >= 0 && x < String.length sa.(y)
|
|
|
|
let gen_string sa (x, y) (dx, dy) =
|
|
let rec impl acc x y =
|
|
if is_inbounds sa (x, y) then
|
|
impl (String.cat acc (String.make 1 sa.(y).[x])) (x + dx) (y + dy)
|
|
else acc
|
|
in
|
|
impl "" x y
|
|
|
|
let gen_strings sa (x, y) (dx, dy) (dx2, d2y) =
|
|
let rec impl acc x y =
|
|
if is_inbounds sa (x, y) then
|
|
let s = gen_string sa (x, y) (dx, dy) in
|
|
impl (s :: acc) (x + dx2) (y + d2y)
|
|
else acc
|
|
in
|
|
List.rev (impl [] x y)
|
|
|
|
let gen_search_strings sa =
|
|
let right = String.length sa.(0) - 1 in
|
|
gen_strings sa (0, 0) (1, 0) (0, 1)
|
|
@ gen_strings sa (0, 0) (0, 1) (1, 0)
|
|
@ gen_strings sa (0, 0) (1, 1) (1, 0)
|
|
@ gen_strings sa (0, 1) (1, 1) (0, 1)
|
|
@ gen_strings sa (right, 0) (-1, 1) (-1, 0)
|
|
@ gen_strings sa (right, 1) (-1, 1) (0, 1)
|
|
@ []
|
|
|
|
let find_xmas sa =
|
|
let search_strings = gen_search_strings sa in
|
|
List.fold_left (fun acc x -> acc + search_string x "XMAS") 0 search_strings
|
|
+ List.fold_left (fun acc x -> acc + search_string x "SAMX") 0 search_strings
|
|
|
|
let find_mas sa x y =
|
|
let find_ms a b c d =
|
|
sa.(y - 1).[x - 1] = a
|
|
&& sa.(y - 1).[x + 1] = b
|
|
&& sa.(y + 1).[x - 1] = c
|
|
&& sa.(y + 1).[x + 1] = d
|
|
in
|
|
sa.(y).[x] = 'A'
|
|
&& (find_ms 'M' 'M' 'S' 'S' || find_ms 'S' 'S' 'M' 'M'
|
|
|| find_ms 'M' 'S' 'M' 'S' || find_ms 'S' 'M' 'S' 'M')
|
|
|
|
let find_mases sa =
|
|
let acc = ref 0 in
|
|
for y = 1 to Array.length sa - 2 do
|
|
for x = 1 to String.length sa.(y) - 2 do
|
|
if find_mas sa x y then acc := !acc + 1
|
|
done
|
|
done;
|
|
!acc
|
|
|
|
let sa_of_file fname = Aoc.strings_of_file fname |> Array.of_list
|
|
|
|
let _ =
|
|
Aoc.main sa_of_file
|
|
[ (string_of_int, find_xmas); (string_of_int, find_mases) ]
|