AoC 2022 - Day4

Mix.install([
  {:kino_aoc, git: "https://github.com/ljgago/kino_aoc"}
])

Setup

{:ok, data} = KinoAOC.download_puzzle("2022", "4", System.fetch_env!("LB_AOC_SECRET"))

Solve

defmodule Day4 do
  def solve(data) do
    data
    |> String.split("\n", trim: true)
    |> Enum.reduce({0, 0}, fn row, {r1, r2} ->
      [s1, s2] = extract(row)

      {t1(r1, s1, s2), t2(r2, s1, s2)}
    end)
  end

  def t1(cnt, s1, s2), do: (is_subset(s1, s2) && cnt + 1) || cnt
  def t2(cnt, s1, s2), do: (is_intersection(s1, s2) && cnt + 1) || cnt

  defp is_subset(s1, s2), do: MapSet.subset?(s1, s2) or MapSet.subset?(s2, s1)
  defp is_intersection(s1, s2), do: s1 |> MapSet.intersection(s2) |> MapSet.size() |> Kernel.>(0)

  def extract(row) do
    row
    |> String.split(["-", ","], trim: true)
    |> Enum.map(&String.to_integer/1)
    |> Enum.chunk_every(2)
    |> Enum.map(fn [a, b] -> Range.new(a, b) |> MapSet.new() end)
  end

  def print_res({r1, r2}, type \\ "Live") do
    IO.puts("#{type} results:")
    IO.puts("Task 1: #{r1}")
    IO.puts("Task 2: #{r2}")
  end
end

Day4.solve(data)

Check

ExUnit.start(autorun: false)

defmodule AoCTest do
  use ExUnit.Case, async: false

  @testd """
  2-4,6-8
  2-3,4-5
  5-7,7-9
  2-8,3-7
  6-6,4-6
  2-6,4-8
  """

  test "solves test cases" do
    assert {2, 4} = Day4.solve(@testd)
  end
end

ExUnit.run()

# {477, 830}
data |> Day4.solve() |> Day4.print_res()