2022 Day 6

Mix.install([:kino])

Input

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

Code

Module

defmodule Tuning do
  def start_marker(input), do: find_marker(input, 4)

  def message_marker(input), do: find_marker(input, 14)

  defp find_marker(input, length) do
    input
    |> process_input()
    |> Enum.chunk_every(length, 1, :discard)
    |> Enum.find_index(fn frame -> Enum.uniq(frame) == frame end)
    |> Kernel.+(length)
  end

  defp process_input(input), do: String.to_charlist(input)
end

Evaluate

part_1 =
  input
  |> Kino.Input.read()
  |> Tuning.start_marker()

part_2 =
  input
  |> Kino.Input.read()
  |> Tuning.message_marker()

{part_1, part_2}

Test

ExUnit.start(autorun: false)

defmodule TuningTest do
  use ExUnit.Case, async: true

  setup do
    data_streams = [
      "mjqjpqmgbljsphdztnvjfqwrcgsmlb",
      "bvwbjplbgvbhsrlpgdmjqwftvncz",
      "nppdvjthqldpwncqszvftbrmjlhg",
      "nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg",
      "zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw"
    ]

    {:ok, data_streams: data_streams}
  end

  test "start_marker", %{data_streams: data_streams} do
    assert Tuning.start_marker(Enum.at(data_streams, 0)) == 7
    assert Tuning.start_marker(Enum.at(data_streams, 1)) == 5
    assert Tuning.start_marker(Enum.at(data_streams, 2)) == 6
    assert Tuning.start_marker(Enum.at(data_streams, 3)) == 10
    assert Tuning.start_marker(Enum.at(data_streams, 4)) == 11
  end

  test "message_marker", %{data_streams: data_streams} do
    assert Tuning.message_marker(Enum.at(data_streams, 0)) == 19
    assert Tuning.message_marker(Enum.at(data_streams, 1)) == 23
    assert Tuning.message_marker(Enum.at(data_streams, 2)) == 23
    assert Tuning.message_marker(Enum.at(data_streams, 3)) == 29
    assert Tuning.message_marker(Enum.at(data_streams, 4)) == 26
  end
end

ExUnit.run()