Day 25

Solution

{:ok, contents} = File.read("#{__DIR__}/inputs/day25.txt")

parse = fn schema ->
  cols =
    schema
    |> String.split("\n", trim: true)
    |> Enum.map(&String.to_charlist/1)
    |> Enum.zip_with(& &1)

  heights = Enum.map(cols, fn col -> Enum.count(col, &(&1 == ?#)) - 1 end)
  type = if Enum.all?(cols, &(hd(&1) == ?#)), do: :lock, else: :key
  {type, heights}
end

input = contents |> String.split("\n\n") |> Enum.map(parse)
[keys, locks] = [:key, :lock] |> Enum.map(&Keyword.get_values(input, &1))

for key <- keys, lock <- locks do
  [key, lock]
  |> Enum.zip_with(fn [k, l] -> k + l <= 5 end)
  |> Enum.all?()
end
|> Enum.count(&amp; &amp;1)