Finish day 4

day4.livemd

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+# AOC 2022 - Template - fork
+
+```elixir
+Mix.install([
+  {:req, "~> 0.3.3"}
+])
+```
+
+## Puzzle description
+
+[Day 4: Camp Cleanup](https://adventofcode.com/2022/day/4).
+
+## Input
+
+```elixir
+defmodule Load do
+  def input do
+    aoc_session = System.fetch_env!("LB_AOC_SESSION")
+    input_url = "https://adventofcode.com/2022/day/4/input"
+    Req.get!(input_url, headers: [cookie: "session=#{aoc_session}"]).body
+  end
+end
+```
+
+## Solution
+
+```elixir
+defmodule Util do
+  def process(input) do
+    input
+    |> String.trim()
+    |> String.split("\n", trim: true)
+    |> Enum.map(&pairs_to_range/1)
+  end
+
+  defp pairs_to_range(pairs) do
+    pairs
+    |> String.split(",")
+    |> Enum.map(&to_range/1)
+  end
+
+  defp to_range(pair) do
+    pair =
+      pair
+      |> String.split("-")
+      |> Enum.map(&String.to_integer/1)
+
+    apply(Range, :new, pair)
+  end
+end
+```
+
+```elixir
+defmodule Part1 do
+  def run(input) do
+    input
+    |> Util.process()
+    |> Enum.reduce(0, fn [first, second], acc ->
+      first = MapSet.new(first)
+      second = MapSet.new(second)
+
+      if MapSet.subset?(first, second) or MapSet.subset?(second, first) do
+        acc + 1
+      else
+        acc
+      end
+    end)
+  end
+end
+
+defmodule Part2 do
+  def run(input) do
+    input
+    |> Util.process()
+    |> Enum.reduce(0, fn [first, second], acc ->
+      first = MapSet.new(first)
+      second = MapSet.new(second)
+
+      if MapSet.disjoint?(first, second) do
+        acc
+      else
+        acc + 1
+      end
+    end)
+  end
+end
+
+ExUnit.start(autorun: false)
+
+defmodule Test do
+  use ExUnit.Case, async: true
+  @example_input ~s(2-4,6-8
+2-3,4-5
+5-7,7-9
+2-8,3-7
+6-6,4-6
+2-6,4-8)
+  @input Load.input()
+
+  test "it loads the input" do
+    assert String.length(@input) > 0
+  end
+
+  test "part 1 example" do
+    assert Part1.run(@example_input) === 2
+  end
+
+  test "part 1" do
+    assert Part1.run(@input) === 441
+  end
+
+  test "part 2 example" do
+    assert Part2.run(@example_input) === 4
+  end
+
+  test "part 2" do
+    assert Part2.run(@input) === 861
+  end
+end
+
+ExUnit.run()
+```