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journeys.ml
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journeys.ml
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type direction = N | E | S | W
type command = L | R | F
let get_direction = function
| "N" -> N
| "E" -> E
| "S" -> S
| "W" -> W
| _ -> failwith "Wrong direction!"
let get_point s =
Core.String.split s ~on:' '
|> function
| [x; y; d] -> (int_of_string x, int_of_string y, get_direction d)
| _ -> failwith "Wrong point!"
let rec to_command_list l = function
| [] -> l
| h :: t ->
let find_command = function
| 'L' -> L
| 'R' -> R
| 'F' -> F
| _ -> failwith "Wrong command!"
in
List.rev @@ to_command_list (find_command h :: l) t
let move c (x, y, d) = match c, d with
| R, N -> (x, y, E)
| R, E -> (x, y, S)
| R, S -> (x, y, W)
| R, W -> (x, y, N)
| L, N -> (x, y, W)
| L, W -> (x, y, S)
| L, S -> (x, y, E)
| L, E -> (x, y, N)
| F, N -> (x, (y + 1), N)
| F, E -> ((x + 1), y, E)
| F, S -> (x, (y - 1), S)
| F, W -> ((x - 1), y, W)
let validate_journey p commands =
let rec aux p = function
| [] -> p
| h :: t -> aux (move h p) t
in aux p (List.rev (to_command_list [] commands))
let rec split_journeys l = function
| ( [] | [_] | [_; _] ) -> l
| s :: (c :: ( e :: t ) ) -> split_journeys ((s, e, c) :: l) t
let rec validate_journeys = function
| [] -> ()
| (s, e, c) :: t ->
let end_point = get_point e in
let commands = Core.String.to_list c in
let calculated_end_point = validate_journey (get_point s) commands in
Printf.printf "%s -> %b\n" e (calculated_end_point = end_point);
validate_journeys t
let () =
Sys.argv.(1) (* first argument for the file name *)
|> Core.In_channel.read_lines
|> List.filter (fun i -> i <> "")
|> split_journeys []
|> List.rev
|> validate_journeys
;;