day 1

Mix.install([:kino])

Section

input = Kino.Input.textarea("input file: ")

input = Kino.Input.read(input)

nums =
  input
  |> String.split()
  |> Enum.map(&(&1 |> String.to_integer()))

part_1 =
  Enum.filter(nums, &Enum.member?(nums, 2020 - &1))
  |> Enum.reduce(1, &(&1 * &2))

IO.puts("part1: #{part_1}")

pairs = for x <- nums, y <- nums, x != y and x + y < 2020, into: %{}, do: {x + y, {x, y}}

part_2 =
  Enum.filter(nums, &amp;Map.has_key?(pairs, 2020 - &amp;1))
  |> Enum.reduce(1, &amp;(&amp;1 * &amp;2))

IO.puts("part2: #{part_2}")