Day 4

Setup

Mix.install([:kino])

input =
  Kino.Input.textarea("Paste input here",
    default: """
    2-4,6-8
    2-3,4-5
    5-7,7-9
    2-8,3-7
    6-6,4-6
    2-6,4-8
    """
  )

sections =
  input
  |> Kino.Input.read()
  |> String.split("\n", trim: true)
  |> Stream.map(&String.split(&1, ","))
  |> Stream.map(fn pair ->
    pair
    |> Stream.map(&String.split(&1, "-"))
    |> Stream.map(&Enum.map(&1, fn s -> String.to_integer(s) end))
    |> Enum.map(&List.to_tuple/1)
  end)
  |> Enum.map(&List.to_tuple/1)

defmodule CampCleanup do
  def fully_contains?({s1, e1}, {s2, e2}) do
    cond do
      s1 >= s2 and e1 <= e2 -> true
      s2 >= s1 and e2 <= e1 -> true
      true -> false
    end
  end

  def partially_contains?({s1, e1}, {s2, e2}) do
    cond do
      e1 >= s2 and s1 <= s2 -> true
      e2 >= s1 and s2 <= s1 -> true
      true -> false
    end
  end
end

Part 1

sections
|> Stream.map(fn {x1, x2} -> CampCleanup.fully_contains?(x1, x2) end)
|> Stream.filter(& &1)
|> Enum.count()

Part 2

sections
|> Stream.map(fn {x1, x2} -> CampCleanup.partially_contains?(x1, x2) end)
|> Enum.map(&IO.inspect/1)
|> Stream.filter(& &1)
|> Enum.count()