From 9cf965cf097d59c88acf7e4a3de2b9b4511a280f Mon Sep 17 00:00:00 2001
From: Caleb Webber <caleb@codingthemsoftly.com>
Date: Tue, 3 Dec 2024 09:26:30 -0500
Subject: [PATCH] add 2024 day 3

---
 elixir/livebook/2024/day3.livemd | 33 ++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 elixir/livebook/2024/day3.livemd

diff --git a/elixir/livebook/2024/day3.livemd b/elixir/livebook/2024/day3.livemd
new file mode 100644
index 0000000..8a2e79a
--- /dev/null
+++ b/elixir/livebook/2024/day3.livemd
@@ -0,0 +1,33 @@
+# AOC 2024 Day 3
+
+## Section
+
+```elixir
+input = File.read!("/data/input.txt")
+```
+
+```elixir
+Regex.scan(
+  ~r/mul\((\d+),(\d+)\)/,
+  input
+)
+|> Stream.map(fn [_, a, b] -> String.to_integer(a) * String.to_integer(b) end)
+|> Enum.sum()
+```
+
+```elixir
+for instruction <- Regex.scan(
+  ~r/(mul\((\d+),(\d+)\)|don't\(\)|do\(\))/,
+  input
+), reduce: {true, 0} do
+  {enabled?, acc} ->
+    (fn
+      false, ["mul" <> _ | _] -> {false, acc}
+      true, ["mul" <> _, _, a, b] -> {true, acc + String.to_integer(a) * String.to_integer(b)}
+      _, ["don" <> _ | _] -> {false, acc}
+      _, ["do()" | _] -> {true, acc}
+    end
+    ).(enabled?, instruction)
+end
+```
+