day06.livemd

Day6

Mix.install([
  {:req, "~> 0.3.0"}
])

Input

# thanks to https://twitter.com/ryoung786/status/1598415749638397962?s=20&t=TLW9UlzqB9uOYhPjuGQuSQ

day = 6
aoc_session = System.fetch_env!("LB_AOC_SESSION_COOKIE")
input_url = "https://adventofcode.com/2022/day/#{day}/input"

input = Req.get!(input_url, headers: [cookie: "session=#{aoc_session}"]).body

Part 1

marker_size = 4

{_, index} =
  input
  |> String.replace("\n", "")
  |> String.codepoints()
  |> Enum.with_index()
  |> Enum.chunk_every(marker_size, 1)
  |> Enum.find(fn list ->
    size =
      list
      |> Enum.uniq_by(&elem(&1, 0))
      |> Enum.count()

    size == marker_size
  end)
  |> List.last()

index + 1

Part 2

marker_size = 14

{_, index} =
  input
  |> String.replace("\n", "")
  |> String.codepoints()
  |> Enum.with_index()
  |> Enum.chunk_every(marker_size, 1)
  |> Enum.find(fn list ->
    size =
      list
      |> Enum.uniq_by(&elem(&1, 0))
      |> Enum.count()

    size == marker_size
  end)
  |> List.last()

index + 1