🎄 Year 2020 🔔 Day 06

Parse input

filename = "#{__DIR__}/../../../inputs/2020/day06.txt"

parsed_input_stream =
  File.stream!(filename)
  |> Enum.map(&String.trim/1)
  |> Enum.chunk_by(fn e -> e == "" end)
  |> Enum.take_every(2)

Shared code

Part One

parsed_input_stream
|> Enum.map(&Enum.join/1)
|> Enum.map(&String.graphemes/1)
|> Enum.map(&Enum.uniq/1)
|> Enum.map(&Enum.count/1)
|> Enum.sum()

Part two

parsed_input_stream
|> Enum.map(fn answers ->
  char_counts =
    answers
    |> Enum.join()
    |> String.graphemes()
    |> Enum.reduce(%{}, fn char, counts ->
      Map.update(counts, char, 1, &(&1 + 1))
    end)
    |> dbg()

  {Enum.count(answers), char_counts}
end)
|> Enum.map(fn {respondent_count, char_counts} ->
  Map.values(char_counts) |> Enum.filter(&(&1 == respondent_count)) |> Enum.count()
end)
|> Enum.sum()