Day 5

Deps & preparation

Mix.install([
  {:kino, "~> 0.4.0"}
])

input = Kino.Input.textarea("Please paste your input file:")

Input

coordinates =
  Kino.Input.read(input)
  |> String.split(["\n", ",", " -> "], trim: true)
  |> Enum.map(&String.to_integer/1)
  |> Enum.chunk_every(4)

Part 1

coordinates
|> Enum.reduce(
  [],
  fn
    [x, y, x1, y1], map when y == y1 ->
      Enum.zip(x..x1, Stream.cycle([y])) ++ map

    [x, y, x1, y1], map when x == x1 ->
      Enum.zip(Stream.cycle([x]), y..y1) ++ map

    _, map ->
      map
  end
)
|> Enum.frequencies()
|> Enum.count(fn {_k, v} -> v > 1 end)

Part 2

coordinates
|> Enum.reduce(
  [],
  fn
    [x, y, x1, y1], map when y == y1 ->
      Enum.zip(x..x1, Stream.cycle([y])) ++ map

    [x, y, x1, y1], map when x == x1 ->
      Enum.zip(Stream.cycle([x]), y..y1) ++ map

    [x, y, x1, y1], map ->
      Enum.zip(x..x1, y..y1) ++ map
  end
)
|> Enum.frequencies()
|> Enum.count(fn {_k, v} -> v > 1 end)