Advent of Code 2024 - Day 03

Mix.install([
  {:req, "~> 0.5"},
  {:benchee, "~> 1.3"}
])

Input

opts = [headers: [{"cookie", "session=#{System.fetch_env!("LB_AOC_SESSION")}"}]]
puzzle_input = Req.get!("https://adventofcode.com/2024/day/3/input", opts).body

Puzzle 1

puzzle_1 = fn ->
  Regex.scan(~r/mul\((\d+),(\d+)\)/, puzzle_input, capture: :all_but_first)
  |> Enum.map(fn [a, b] ->
    String.to_integer(a) * String.to_integer(b)
  end)
  |> Enum.sum()
end

puzzle_1.()

Puzzle 2

puzzle_2 = fn ->
  Regex.scan(~r/mul\((-?\d+),(-?\d+)\)|do(?:n't)?\(\)/, puzzle_input)
  |> Enum.reduce({0, :enabled}, fn
    ["don't()"], {count, _status} ->
      {count, :disabled}

    ["do()"], {count, _status} ->
      {count, :enabled}

    [_text, a, b], {count, :enabled} ->
      result = String.to_integer(a) * String.to_integer(b)

      {result + count, :enabled}

    [_text, _a, _b], {count, :disabled} ->
      {count, :disabled}
  end)
  |> elem(0)
end

puzzle_2.()

Benchmarks

Benchee.run(%{
  "puzzle_1" => fn -> puzzle_1.() end,
  "puzzle_2" => fn -> puzzle_2.() end
})