Day 18

Mix.install([
  {:req, "~> 0.3.2"},
  {:vega_lite, "~> 0.1.6"},
  {:kino_vega_lite, "~> 0.1.6"}
])

alias VegaLite, as: Vl

day = 18

aoc_session = System.fetch_env!("LB_AOC_SESSION")
input_url = "https://adventofcode.com/2022/day/#{day}/input"
{:ok, %{body: input}} = Req.get(input_url, headers: [cookie: "session=#{aoc_session}"])

Part 1

test_input = """
2,2,2
1,2,2
3,2,2
2,1,2
2,3,2
2,2,1
2,2,3
2,2,4
2,2,6
1,2,5
3,2,5
2,1,5
2,3,5
"""

to_xyz = fn line ->
  [x, y, z] = String.split(line, ",", trim: true)
  {String.to_integer(x), String.to_integer(y), String.to_integer(z)}
end

to_xyz.("4,5,6")

exposed_surfaces = fn cubes, {x, y, z} ->
  6 -
    Enum.count(cubes, fn
      {^x, ^y, ^z} -> false
      {^x, ^y, z2} -> abs(z - z2) == 1
      {^x, y2, ^z} -> abs(y - y2) == 1
      {x2, ^y, ^z} -> abs(x - x2) == 1
      _ -> false
    end)
end

cubes = [{1, 1, 1}, {2, 1, 1}]
exposed_surfaces.(cubes, {2, 3, 1})

# input = test_input

cubes =
  input
  |> String.split("\n", trim: true)
  |> Enum.map(&to_xyz.(&1))

Enum.map(cubes, &exposed_surfaces.(cubes, &1))
|> Enum.sum()

Part 2