Day 01 of AoC 2024

first_star.exs

input
#example
|> String.split("\n", trim: true)
|> Enum.map(fn line ->
  line
  |> String.split(" ", trim: true)
  |> Enum.map(&String.to_integer/1)
  |> List.to_tuple()
end)
|> Enum.unzip()
|> Tuple.to_list()
|> Enum.map(&Enum.sort/1)
|> Enum.zip()
|> Enum.map(fn {a, b} -> abs(a - b) end)
|> Enum.sum()

second_star.exs

{left_list, right_list} =
  input
  #example
  |> String.split("\n", trim: true)
  |> Enum.map(fn line ->
    line
    |> String.split(" ", trim: true)
    |> Enum.map(&String.to_integer(&1))
    |> List.to_tuple()
  end)
  |> Enum.unzip()
right_map = right_list |> Enum.group_by(& &1) |> Map.new(fn {k, v} -> {k, Enum.count(v)} end)

Enum.reduce(left_list, 0, fn el, acc -> acc + el * Map.get(right_map, el, 0) end)