day13.ml

  let run tiles program =
    let tiles = ref tiles in
    let score = ref 0L in
    let prev_ball = ref (find Ball !tiles) in
    let x_pad_desired, y_pad = find HPaddle !tiles in
    let x_pad_desired = ref x_pad_desired in
    let update_ball_line (x2, y2) =
      let (x1, y1) = !prev_ball in
      printf "BALL: (%Ld, %Ld) => (%Ld, %Ld)\n" x1 y1 x2 y2;
      printf "(Y = %Ld) XPAD: %Ld => " y_pad !x_pad_desired;
      let () =
        match compare (x1, y1) (x2, y2) with
        | 0 -> ()
        | _ ->
          let x_step = x2 - x1 in
          x_pad_desired := x1 + x_step * (Int64.abs (y2 - y_pad));
      in
      prev_ball := (x2, y2);
      printf "XPAD: %Ld \n" !x_pad_desired;
    in
    let get_input () =
      printf "\n";
      print_game !tiles;
      let step = compare !x_pad_desired (find HPaddle !tiles |> fst) in
      printf "JOYSTICK: %d\n" step;
      Int64.of_int step
    in
    let state = Intcode.init get_input program in
    let rec run () =
      match Intcode.run_till_output state with
      | `Halted ->
        printf "Part2 = %Ld\n" !score;
        print_game !tiles
      | `Output ->
        let x = Intcode.consume_output state in
        match Intcode.run_till_output state with
        | `Halted -> failwith "no second input"
        | `Output ->
          let y = Intcode.consume_output state in
          match Intcode.run_till_output state with
          | `Halted -> failwith "no third input"
          | `Output ->
            let () =
              match x,y with
              | -1L, 0L -> score := Intcode.consume_output state
              | _ ->
              let block = match Intcode.consume_output state with
                | 0L -> Empty
                | 1L -> Wall
                | 2L -> Block
                | 3L -> HPaddle
                | 4L ->
                  update_ball_line (x, y);
                  Ball
                | n -> failwith @@ sprintf "Unknown block %Ld" n
              in
              tiles := M.add (x, y) block !tiles;
            in
            run ()
    in
    run ();
    !tiles
  in