day2.exs

inp
  |> String.split("\n", trim: true)
  |> Enum.map(&String.split(&1, "\t"))
  |> Enum.map(fn a -> a |> Enum.map(&String.to_integer/1) end)
  |> Enum.map(fn a -> [Enum.max(a), Enum.min(a)] end)
  |> Enum.map(fn [a, b] -> a - b end)
  |> Enum.sum()
  |> IO.inspect()

defmodule Helper do
  def combination(0, _), do: [[]]
  def combination(_, []), do: []
  def combination(n, [x|xs]) do
    (for y <- combination(n - 1, xs), do: [x|y]) ++ combination(n, xs)
  end
end

inp
  |> String.split("\n")
  |> Enum.map(&String.split(&1, "\t"))
  |> Enum.map(fn a -> a |> Enum.map(&String.to_integer/1) end)
  |> Enum.map(&Helper.combination(2, &1))
  |> Enum.map(&Enum.map(&1, fn l -> l |> Enum.sort() |> Enum.reverse() end))
  |> Enum.map(&Enum.filter(&1, fn [a, b] -> rem(a, b) == 0 && a != b end))
  |> Enum.map(&Enum.map(&1, fn [a, b] -> a / b end))
  |> List.flatten()
  |> Enum.sum()
  |> IO.inspect()