Day 9: Movie Theater

Mix.install([:kino])

Section

input = Kino.Input.textarea("input", monospace: true)

input
|> Kino.Input.read()
|> String.split([",", "\n"], trim: true)
|> Enum.map(&String.to_integer/1)
|> Enum.chunk_every(2)
|> Enum.map(&List.to_tuple/1)
|> then(fn tiles ->
  for t1 <- tiles,
      t2 <- tiles,
      t1 < t2,
      do: {t1, t2}
end)
|> Enum.map(fn {{x1, y1}, {x2, y2}} ->
  Enum.count(Range.new(x1, x2)) * Enum.count(Range.new(y1, y2))
end) 
|> Enum.max()

input
|> Kino.Input.read()
|> String.split([",", "\n"], trim: true)
|> Enum.map(&String.to_integer/1)
|> Enum.chunk_every(2)
|> Enum.map(&List.to_tuple/1)
|> then(fn polygon ->
  Enum.flat_map_reduce(polygon, tl(polygon) ++ [hd(polygon)], fn {x1, y1}, rectangles ->
    {
      Enum.reduce(rectangles, [], fn {x2, y2}, acc ->
        if not (polygon
                |> Enum.chunk_every(2, 1, [hd(polygon)])
                |> Enum.any?(fn
                  [{x3, y3}, {x4, y4}] ->
                    max(y3, y4) > min(y1, y2) and
                    min(y3, y4) < max(y1, y2) and
                    max(x3, x4) > min(x1, x2) and
                    min(x3, x4) < max(x1, x2)
                end)) do
          [(abs(x2 - x1) + 1) * (abs(y2 - y1) + 1) | acc]
        else
          acc
        end
      end),
      tl(rectangles)
    }
  end)
end)
|> elem(0)
|> Enum.max()