Yea, MapSet all the way on this one 
defmodule ExAOC2022.Day4 do
@input "./lib/day4_input.txt"
def puzzle1() do
@input
|> file_by_line()
|> Enum.map(&line_to_elfarea/1)
|> Enum.map(&subset?/1)
|> Enum.reject(& !&1)
|> length()
end
def puzzle2() do
@input
|> file_by_line()
|> Enum.map(&line_to_elfarea/1)
|> Enum.map(&intersect?/1)
|> Enum.reject(& !&1)
|> length()
end
defp line_to_elfarea(line) do
line
|> String.split(",")
|> IO.inspect()
|> Enum.map(&to_map_set/1)
end
defp to_map_set(area_str) do
[first, last] = String.split(area_str, "-")
Range.new(String.to_integer(first), String.to_integer(last))
|> Enum.to_list
|> MapSet.new()
end
defp subset?([one, two]) do
MapSet.subset?(one, two) || MapSet.subset?(two, one)
end
defp intersect?([one, two]) do
MapSet.size(MapSet.intersection(one, two)) > 0
end
defp file_by_line(file) do
file
|> File.read!()
|> String.split(~r/\R/, trim: true)
end
end
