defmodule Day04 do
import Enum, only: [filter: 2, chunk_by: 2, any?: 2, sort: 1]
def run(cnd), do: 124_075..580_769 |> filter(&valid?(Integer.digits(&1), cnd)) |> length()
defp valid?(ds, cnd), do: chunk_by(ds, & &1) |> any?(&cnd.(length(&1))) and sort(ds) == ds
end
IO.inspect(Day04.run(&(&1 >= 2)), label: "part 1")
IO.inspect(Day04.run(&(&1 == 2)), label: "part 2")
