Day 10: Cathode-Ray Tube

Mix.install([:kino])

Section

input = Kino.Input.textarea("input")

instructions =
  input
  |> Kino.Input.read()
  |> String.split("\n")
  |> Stream.transform([], fn
    "addx " <> v, acc ->
      {[:noop, String.to_integer(v)], acc}

    "noop", acc ->
      {[:noop], acc}
  end)

[20, 60, 100, 140, 180, 220]
|> Enum.map(fn x ->
  instructions
  |> Stream.take(x - 1)
  |> Enum.reduce(1, fn
    :noop, register ->
      register

    v, register ->
      v + register
  end)
  |> Kernel.*(x)
end)
|> Enum.sum()

instructions
|> Enum.with_index(fn e, i -> {e, rem(i, 40)} end)
|> Enum.map_reduce(1, fn
  {:noop, i}, v ->
    {i in (v - 1)..(v + 1), v}

  {x, i}, v ->
    {i in (v - 1)..(v + 1), v + x}
end)
|> elem(0)
|> Enum.chunk_every(40)
|> Enum.each(fn row ->
  row
  |> Enum.map(fn
    true -> "#"
    false -> " "
  end)
  |> Enum.join()
  |> IO.puts()
end)