1.exs

priorities = String.graphemes("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")

System.argv()
|> List.first()
|> File.stream!()
|> Enum.reduce(0, fn inventory, total ->
  items = inventory |> String.trim() |> String.graphemes()

  {compartment_1, compartment_2} = Enum.split(items, items |> Enum.count() |> Integer.floor_div(2))

  duplicate_item = Enum.find(compartment_1, & Enum.member?(compartment_2, &1))

  total + Enum.find_index(priorities, & &1 == duplicate_item) + 1
end)
|> IO.inspect()

2.exs

priorities = String.graphemes("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")

System.argv()
|> List.first()
|> File.stream!()
|> Enum.map(& &1 |> String.trim() |> String.graphemes() |> MapSet.new())
|> Enum.chunk_every(3)
|> Enum.reduce(0, fn group, total ->
  badge =
    group
    |> Enum.reduce(&MapSet.intersection/2)
    |> MapSet.to_list()
    |> List.first()

  total + Enum.find_index(priorities, & &1 == badge) + 1
end)
|> IO.inspect()