Day 2 part 1

day2.livemd

@@ -0,0 +1,112 @@
+# AOC 2022 - Day 2
+
+```elixir
+Mix.install([
+  {:req, "~> 0.3.3"}
+])
+```
+
+## Puzzle description
+
+[Day 2: Rock Paper Scissors](https://adventofcode.com/2022/day/2).
+
+## Input
+
+```elixir
+defmodule Load do
+  def input do
+    aoc_session = System.fetch_env!("LB_AOC_SESSION")
+    input_url = "https://adventofcode.com/2022/day/2/input"
+    Req.get!(input_url, headers: [cookie: "session=#{aoc_session}"]).body
+  end
+end
+```
+
+## Solution
+
+<!-- livebook:{"reevaluate_automatically":true} -->
+
+```elixir
+defmodule Util do
+  def process(input) do
+    input
+    |> String.split("\n", trim: true)
+    |> Enum.map(fn entry ->
+      entry
+      |> String.split()
+      |> Enum.map(fn
+        symbol when symbol in ["A", "X"] -> :rock
+        symbol when symbol in ["B", "Y"] -> :paper
+        symbol when symbol in ["C", "Z"] -> :scissors
+      end)
+    end)
+  end
+
+  # Check your opponent vs you
+  def check_pair(:rock, :rock), do: :draw
+  def check_pair(:rock, :paper), do: :win
+  def check_pair(:rock, :scissors), do: :lose
+  def check_pair(:paper, :rock), do: :lose
+  def check_pair(:paper, :paper), do: :draw
+  def check_pair(:paper, :scissors), do: :win
+  def check_pair(:scissors, :rock), do: :win
+  def check_pair(:scissors, :paper), do: :lose
+  def check_pair(:scissors, :scissors), do: :draw
+
+  def points(:win), do: 6
+  def points(:draw), do: 3
+  def points(:lose), do: 0
+  def points(:rock), do: 1
+  def points(:paper), do: 2
+  def points(:scissors), do: 3
+end
+```
+
+```elixir
+defmodule Part1 do
+  def run(input) do
+    Util.process(input)
+    |> Enum.map(fn [they, you] -> {you, Util.check_pair(they, you)} end)
+    |> Enum.map(fn {played, result} -> Util.points(played) + Util.points(result) end)
+    |> Enum.sum()
+  end
+end
+
+defmodule Part2 do
+  def run(input) do
+    0
+  end
+end
+
+ExUnit.start(autorun: false)
+
+defmodule Test do
+  use ExUnit.Case, async: true
+  @example_input ~s(A Y
+B X
+C Z)
+  @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) === 15
+  end
+
+  test "part 1" do
+    assert Part1.run(@input) === 13052
+  end
+
+  test "part 2 example" do
+    assert Part2.run(@example_input) === 12
+  end
+
+  test "part 2" do
+    assert Part2.run(@input) === 0
+  end
+end
+
+ExUnit.run()
+```