From d09cd32bd74e5eab540f1d7179d394e31ae69296 Mon Sep 17 00:00:00 2001
From: Rebecca Le <traybaby@gmail.com>
Date: Thu, 19 Dec 2024 17:19:42 +0800
Subject: [PATCH] 2024 day 19 - use async streams to speed things up
 dramatically

---
 lib/y2024/README.md | 4 ++--
 lib/y2024/day19.ex  | 9 +++++----
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/lib/y2024/README.md b/lib/y2024/README.md
index b352a01..4defaa8 100644
--- a/lib/y2024/README.md
+++ b/lib/y2024/README.md
@@ -48,6 +48,6 @@ day 16, part 2         13.07       76.51 ms     ±5.00%       76.09 ms       85.
 day 17, part 1       45.64 K       21.91 μs    ±15.81%       21.17 μs       37.50 μs
 day 18, part 1         22.53       44.38 ms     ±5.11%       44.48 ms       48.54 ms
 day 18, part 2          4.04      247.58 ms     ±3.18%      247.68 ms      260.90 ms
-day 19, part 1          4.30      232.82 ms     ±1.78%      230.67 ms      240.83 ms
-day 19, part 2          4.31      232.07 ms     ±0.63%      231.50 ms      236.27 ms
+day 19, part 1         29.38       34.03 ms     ±0.86%       34.01 ms       35.47 ms
+day 19, part 2         29.36       34.06 ms     ±1.18%       34.03 ms       36.73 ms
 ```
diff --git a/lib/y2024/day19.ex b/lib/y2024/day19.ex
index bd48eee..68b0923 100644
--- a/lib/y2024/day19.ex
+++ b/lib/y2024/day19.ex
@@ -2,16 +2,17 @@ defmodule Y2024.Day19 do
   use Advent.Day, no: 19
 
   def part1(%{from: from_towels, to: to_towels}) do
-    Enum.count(to_towels, fn to ->
-      ways_to_make(to, from_towels) != 0
+    Task.async_stream(to_towels, fn to ->
+      ways_to_make(to, from_towels)
     end)
+    |> Enum.count(fn {:ok, count} -> count != 0 end)
   end
 
   def part2(%{from: from_towels, to: to_towels}) do
-    Enum.map(to_towels, fn to ->
+    Task.async_stream(to_towels, fn to ->
       ways_to_make(to, from_towels)
     end)
-    |> Enum.sum()
+    |> Enum.reduce(0, fn {:ok, count}, acc -> acc + count end)
   end
 
   def ways_to_make(to, from_towels) do