Advent Of Code

1199 readers

1 users here now

An unofficial home for the advent of code community on programming.dev! Other challenges are also welcome!

Advent of Code is an annual Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like.

Everybody Codes is another collection of programming puzzles with seasonal events.

AoC 2025

Solution Threads

M	T	W	T	F	S	S
1	2	3	4	5	6	7
8	9	10	11	12

Visualisations Megathread

Rules/Guidelines

Follow the programming.dev instance rules
Keep all content related to advent of code in some way
If what youre posting relates to a day, put in brackets the year and then day number in front of the post title (e.g. [2024 Day 10])
When an event is running, keep solutions in the solution megathread to avoid the community getting spammed with posts

Relevant Communities

Relevant Links

Advent of Code Homepage

Credits

Icon base by Lorc under CC BY 3.0 with modifications to add a gradient

console.log('Hello World')

founded 2 years ago

MODERATORS

Ategon@programming.dev

Sigmatics@lemmy.ca

CameronDev@programming.dev

hades@programming.dev

👻 - 2024 DAY 19 SOLUTIONS -👻 (programming.dev)

submitted 1 year ago by CameronDev@programming.dev to c/advent_of_code@programming.dev

33 comments fedilink hide all child comments

Day 19 - Linen Layout

Megathread guidelines

Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
You can send code in code blocks by using three backticks, the code, and then three backticks or use something such as https://topaz.github.io/paste/ if you prefer sending it through a URL

FAQ

What is this?: Here is a post with a large amount of details: https://programming.dev/post/6637268
Where do I participate?: https://adventofcode.com/
Is there a leaderboard for the community?: We have a programming.dev leaderboard with the info on how to join in this post: https://programming.dev/post/6631465

you are viewing a single comment's thread
view the rest of the comments

[–] CameronDev@programming.dev 2 points 1 year ago (1 children)

How fast was the regex approach?

[–] Gobbel2000@programming.dev 3 points 1 year ago (1 children)

About 3ms. A manual implementation might be a bit faster, but not by much. The regex crate is quite optimized for pretty much these problems.

[–] CameronDev@programming.dev 2 points 1 year ago* (last edited 1 year ago) (1 children)

Wow, that is very fast, nice. I was happy with 120ms, seems I'm leaving a lot of performance on the table.

Edit: Regex cut my total time in half, but I am measuring the whole execution, still a massive improvement.

[–] Gobbel2000@programming.dev 3 points 1 year ago (1 children)

The 3ms are for part 1 only, part 2 takes around 27ms. But I see that our approaches there are very similar. One difference that might make an impact is that you copy the substrings for inserting into the hashmap into Strings.

[–] CameronDev@programming.dev 2 points 1 year ago* (last edited 1 year ago)

Removing the string copy with the length->count array from @sjmulder saved me 20ms, so not super significant. I'll have to play the the profiler and see what I am doing wrong.

I think your approach looks a lot more Rust-like, which I like. Part 1 in 4 lines is very nice.