2023 Day 12

Mix.install([
  {:req, "~> 0.4.5"},
  {:vega_lite, "~> 0.1.8"},
  {:kino_vega_lite, "~> 0.1.11"}
])

alias VegaLite, as: Vl

defmodule AOC do
  @aoc_session System.fetch_env!("LB_AOC_SESSION")

  def day(day, year) when day in 1..25 do
    headers = [cookie: "session=#{@aoc_session}"]
    req = Req.new(base_url: "https://adventofcode.com/#{year}/day/#{day}", headers: headers)
    input = Req.get!(req, url: "/input").body

    if input =~ "Please don't repeatedly request this endpoint before it unlocks",
      do: {:error, "Day #{day} hasn't been unlocked yet"},
      else: {:ok, %{req: req, input: input}}
  end

  def submit(answer, %{req: req}, part \\ :part_1) when part in [:part_1, :part_2] do
    part = if part == :part_2, do: 2, else: 1

    if !part_already_completed?(part, req) do
      body = Req.post!(req, url: "/answer", form: [level: part, answer: answer]).body

      cond do
        body =~ "That's the right answer" -> {:correct, answer}
        body =~ "your answer is too low" -> {:too_low, answer}
        body =~ "your answer is too high" -> {:too_high, answer}
        :else -> {:incorrect, answer}
      end
    else
      {:already_completed_part, answer}
    end
  end

  defp part_already_completed?(part, req) do
    body = Req.get!(req).body

    cond do
      body =~ "Both parts of this puzzle are complete!" -> true
      body =~ "The first half of this puzzle is complete!" -> part == 1
      :else -> false
    end
  end

  def nums(str) do
    Regex.scan(~r/\d+/, str) |> Enum.map(fn [x] -> String.to_integer(x) end)
  end
end

{:ok, day} = AOC.day(12, 2023)

Part 1

test_input = """
???.### 1,1,3
.??..??...?##. 1,1,3
?#?#?#?#?#?#?#? 1,3,1,6
????.#...#... 4,1,1
????.######..#####. 1,6,5
?###???????? 3,2,1
"""

defmodule P1 do
  def solve(input) do
    input
    |> String.replace(".", "o")
    |> String.replace("#", "B")
    |> String.split("\n", trim: true)
    |> Enum.map(&parse/1)
    |> Enum.map(&possible_arraingements/1)
    |> Enum.sum()
  end

  def parse(str), do: {str |> String.split(" ") |> hd(), AOC.nums(str)}

  def perms(str), do: perms(String.graphemes(str), []) |> List.flatten()
  def perms([], acc), do: acc |> Enum.reverse() |> Enum.join()
  def perms(["?" | rest], acc), do: [perms(rest, ["B" | acc]), perms(rest, ["o" | acc])]
  def perms([a | rest], acc), do: perms(rest, [a | acc])

  def possible_arraingements({pattern, nums}) do
    re = nums_to_regex(nums)

    pattern
    |> perms()
    |> Enum.count(&Regex.match?(re, &1))
  end

  def nums_to_regex(nums) do
    mid =
      nums
      |> Enum.map(fn v -> "B{#{v}}" end)
      |> Enum.join("o+")

    ~r/^o*#{mid}o*$/
  end
end

# ".??..??...?##. 1,1,3" |> P1.solve()
# test_input |> P1.solve()
day.input |> P1.solve() |> AOC.submit(day)

Part 2

defmodule P2 do
  def solve(input) do
    input
  end
end

test_input |> P2.solve()
# day.input |> P2.solve()

_foo = """
???.### 1,1,3
.??..??...?##. 1,1,3
?#?#?#?#?#?#?#? 1,3,1,6
????.#...#... 4,1,1
????.######..#####. 1,6,5
?###???????? 3,2,1
"""

str = "?????##????.????#??????"

defmodule Foo do
  def perms(str), do: perms(String.graphemes(str), []) |> List.flatten()
  def perms([], acc), do: acc |> Enum.reverse() |> Enum.join()
  def perms(["?" | rest], acc), do: [perms(rest, ["#" | acc]), perms(rest, ["." | acc])]
  def perms([a | rest], acc), do: perms(rest, [a | acc])
end

Foo.perms(str) |> Enum.count()