day09.ml

type state = Clean | Garbage

type stream = {
  state : state;
  ignore : bool;
  score : int;
  nr_chars : int;
  depth : int;
}

let solution =
  let initial_state =
    { state = Clean; ignore = false; score = 0; nr_chars = 0; depth = 1 }
  in
  CCIO.(with_in "inputs/09.txt" read_all)
  |> CCString.to_list
  |> List.fold_left
    (fun ({ depth = d; score = s; nr_chars = n; state = st; _ } as pos) x ->
       match x with
       | _ when pos.ignore -> { pos with ignore = false }
       | '!' -> { pos with ignore = true }
       | '<' when st = Clean -> { pos with state = Garbage }
       | '>' when st = Garbage -> { pos with state = Clean }
       | '{' when st = Clean -> { pos with depth = d + 1; score = s + d }
       | '}' when st = Clean -> { pos with depth = d - 1 }
       | _ when st = Garbage -> { pos with nr_chars = n + 1 }
       | _ -> pos)
    initial_state


let () = Printf.printf "%d\n%d\n" solution.score solution.nr_chars