Day 2

lib/common.ex

@@ -1,4 +1,15 @@
 defmodule Aoc2023.Common do
   def stringify(s) when is_binary(s) do s end
   def stringify(n) when is_integer(n) do inspect(n) end
+  def stringify(nil), do: "nil"
+
+  def map_nth(tup, n, fun) do
+    put_elem(tup, n, fun.(elem(tup, n)))
+  end
+
+  defmacro pipe(expr) do
+    quote do
+      fn (val) -> val |> unquote(expr) end
+    end
+  end
 end

lib/day2.ex

@@ -0,0 +1,52 @@
+defmodule Aoc2023.Day2 do
+  use Aoc2023
+
+  def parse(input) do
+    input
+    |> String.split("\n")
+    |> Enum.map(pipe(
+        String.split(": ")
+        |> then(fn ["Game " <> id, rounds] ->
+          {String.to_integer(id),
+           rounds
+           |> String.split("; ")
+           |> Enum.map(pipe(
+               String.split(", ")
+               |> Enum.map(pipe(
+                   String.split(" ")
+                   |> then(fn [n, color] ->
+                     {String.to_existing_atom(color), String.to_integer(n)}
+                   end)
+               ))
+           ))}
+        end)
+    ))
+    |> Enum.into(%{})
+  end
+
+  @part1_available [
+    red: 12, green: 13, blue: 14
+  ]
+  def part1(input) do
+    input
+    |> Enum.filter(pipe(
+      elem(1)
+      |> Enum.all?(pipe(
+         Enum.all?(fn {color, num} -> Keyword.get(@part1_available, color, 0) >= num end)
+      ))
+    ))
+    |> Enum.map(pipe(elem(0)))
+    |> Enum.sum
+  end
+
+  def part2(input) do
+    input
+    |> Enum.map(pipe(
+      elem(1)
+      |> Enum.reduce(&(Keyword.merge(&1, &2, fn _, m1, m2 -> max(m1, m2) end)))
+      |> Enum.map(pipe(elem(1)))
+      |> Enum.product
+    ))
+    |> Enum.sum
+  end
+end

lib/mix_tasks.ex

@@ -3,14 +3,18 @@ defmodule Mix.Tasks.Aoc do
   import Aoc2023.Common
 
   defp module(1), do: Aoc2023.Day1
+  defp module(2), do: Aoc2023.Day2
   # [MODULE INSERTION POINT]  
 
   defp base_dir(), do: System.get_env("AOC_BASE")
 
   defp tests(day) do
     case File.ls(tests_dir(day)) do
-      {:ok, paths} -> paths |> Enum.filter(&(not String.contains?(&1, ".")))
+      {:ok, paths} ->
-      {:error, e} -> dbg(e)
+        paths |> Enum.filter(&(not String.contains?(&1, ".")))
+
+      {:error, e} ->
+        dbg(e)
         []
     end
   end
@@ -59,17 +63,17 @@ defmodule Mix.Tasks.Aoc do
   defp run(day, ["new"]) do
     create_file("#{base_dir()}/lib/day#{day}.ex", """
     defmodule Aoc2023.Day#{day} do
-    	use Aoc2023
+      use Aoc2023
 
-    	def parse(input) do
+      def parse(input) do
-    		input
+        input
-    	end
+      end
 
-    	def part1(input) do
+      def part1(_input) do
-    	end
+      end
 
-    	def part2(input) do
+      def part2(_input) do
-    	end
+      end
     end
     """)
 
@@ -110,6 +114,8 @@ defmodule Mix.Tasks.Aoc do
         if stringify(p1) != p1e do
           IO.puts("Failed at #{test}.1: expected #{p1e}, got:")
           dbg(p1)
+        else
+          IO.puts("Test #{test}.1 succeeded")
         end
       else
         IO.puts("Test #{test}.1")
@@ -122,6 +128,8 @@ defmodule Mix.Tasks.Aoc do
         if stringify(p2) != p2e do
           IO.puts("Failed at #{test}.2: expected #{p2e}, got:")
           dbg(p2)
+        else
+          IO.puts("Test #{test}.2 succeeded")
         end
       else
         IO.puts("Test #{test}.2")

shell.nix

@@ -5,10 +5,11 @@
   elixir,
   elixir-ls,
   inotify-tools,
+  entr,
 }:
 mkShell {
   packages =
-    [elixir elixir-ls]
+    [elixir elixir-ls entr]
     ++ lib.lists.optional (pkgs.system == "x86_64-linux") inotify-tools
     ++ lib.lists.optionals (pkgs.system == "aarch64-darwin") (with pkgs.darwin.apple_sdk.frameworks; [
       CoreFoundation

tests/day2/1

@@ -0,0 +1,5 @@
+Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green
+Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue
+Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red
+Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red
+Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green

tests/day2/1.1

@@ -0,0 +1 @@
+8

tests/day2/1.2

@@ -0,0 +1 @@
+2286