Day 3

Mix.install([
  {:kino, "~> 0.7.0"}
])

Section

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

lower_case = for x <- ?a..?z, do: <>
upper_case = for x <- ?A..?Z, do: <>

value_key =
  (lower_case ++ upper_case)
  |> Enum.zip(1..52)
  |> Enum.into(%{})

input
|> Kino.Input.read()
|> String.split("\n", trim: true)
|> Enum.map(fn packs ->
  pack_size = packs |> String.length() |> Kernel./(2) |> round
  <> = packs
  [pack1, pack2]
end)
|> Enum.map(fn [pack1, pack2] ->
  pack1
  |> String.split(~r//, trim: true)
  |> Enum.reduce_while(:pending, fn item, _acc ->
    if String.contains?(pack2, item), do: {:halt, item}, else: {:cont, :pending}
  end)
end)
|> Enum.map(fn duplicate_item ->
  value_key[duplicate_item]
end)
|> Enum.sum()

input
|> Kino.Input.read()
|> String.split("\n", trim: true)
|> Enum.chunk_every(3)
|> Enum.map(fn group ->
  [elf1, elf2, elf3] =
    group
    |> Enum.sort_by(&String.length/1)

  elf1
  |> String.split(~r//, trim: true)
  |> Enum.uniq()
  |> Enum.reduce_while(:pending, fn item, _acc ->
    if String.contains?(elf2, item) && String.contains?(elf3, item) do
      {:halt, item}
    else
      {:cont, :pending}
    end
  end)
end)
|> Enum.map(fn duplicate_item ->
  value_key[duplicate_item]
end)
|> Enum.sum()