Day 4

Mix.install([
  {:kino_aoc, git: "https://github.com/ljgago/kino_aoc"}
])

Helper

{:ok, puzzle_input} = KinoAOC.download_puzzle("2022", "4", System.fetch_env!("LB_AOC_SESSION"))

puzzle_input =
  puzzle_input
  |> String.split("\n", trim: true)
  |> Enum.map(fn ranges ->
    [first_range, second_range] = String.split(ranges, ",")
    [first_range_start, first_range_end] = String.split(first_range, "-")
    [second_range_start, second_range_end] = String.split(second_range, "-")
    first_range = String.to_integer(first_range_start)..String.to_integer(first_range_end)
    second_range = String.to_integer(second_range_start)..String.to_integer(second_range_end)
    {MapSet.new(first_range), MapSet.new(second_range)}
  end)

Part 1

puzzle_input
|> Enum.reduce(0, fn {first_range, second_range}, sum ->
  case MapSet.subset?(first_range, second_range) ||
         MapSet.subset?(second_range, first_range) do
    false -> sum
    true -> sum + 1
  end
end)

Part 2

puzzle_input
|> Enum.reduce(0, fn {first_range, second_range}, sum ->
  case MapSet.disjoint?(first_range, second_range) do
    false -> sum + 1
    true -> sum
  end
end)