Advent of Code 2025

adventofcode.com

1208 points by vismit2000 2 days ago


PaulRobinson - 2 days ago

Advent of Code is one of the highlights of December for me.

It's sad, but inevitable, that the global leaderboard had to be pulled. It's also understandable that this year is just 12 days, so takes some pressure off.

If you've never done it before, I recommend it. Don't try and "win", just enjoy the problem solving and the whimsy.

jjice - 2 days ago

I _love_ the Advent of Code. I actually (selfishly) love that it's only 12 days this year, because by about half way, I'm struggling to find the time to sit down and do the fantastic problems because of all the holiday activities IRL.

Huge thanks to those involved!

noirscape - 2 days ago

Taking out the public leaderboard makes sense imo. Even when you don't consider the LLM problem, the public Leaderboard's design was never really suited for anyone outside of the very specific short list of (US) timezones where competing for a quick solution was every feasible.

One thing I do think would be interesting is to see solution rate per hour block. It'd give an indication of how popular advent of code is across the world.

perlperson - 2 days ago

Historical note: the original coding advent calendar was the Perl Advent Calendar, started in 2000 and still going.

https://perladvent.org/archives.html

Advent of Code is awesome also of course -- and was certainly inspired by it.

henhouseai - 6 hours ago

I am glad to have found this thread bc I had never heard of AoC before. I ended up running through Day 1 just in time to catch Day 2 at midnight and so did that one too. I am definitely looking forward to the next 10 days now.

Having only started using python in the last few months (and always alongside agents to help me learn the new language) I am enjoying this opportunity/invitation to challenge myself to write the code from scratch, because it is helping me reinforce my understanding of the fundamentals of a language that is new to me.

On the one hand I do love how (in general nowadays) I can tell an agent to “implement a grammar parser for this example input stream” yet on the other hand, it’s too easy to just use the code without bothering to understand how it works. Likewise, it is so pleasantly easy these days to paste an error message into a chat window instead of figuring out for myself what it means / how to fix it. I love being able to get help (from agents) with that kind of stuff, but I also love being able to do it on my own.

Thank you to the folks who organize this event, for giving me that extra motivation to tie a ribbon around my understanding of various topics enough to be able to write python without help from agents or reference guides.

I’d also like to add that having never participated when the global leaderboard existed, I cannot compare this to that, other than to say that I appreciate how this way encourages me to come up with “personal challenges” like not using an IDE with autocomplete, or not looking up any info from reference sources, or not including any libraries beyond the core language functionality.

fainpul - 2 days ago

Opinion poll:

Python is extremely suitable for these kind of problems. C++ is also often used, especially by competitive programmers.

Which "non-mainstream" or even obscure languages are also well suited for AoC? Please list your weapon of choice and a short statement why it's well suited (not why you like it, why it's good for AoC).

gray_-_wolf - 2 days ago

I am very happy that we get the advent of code again this year, however I have read the FAQ for the first time, and I must admit I am not sure I understand the reasoning behind this:

> If you're posting a code repository somewhere, please don't include parts of Advent of Code like the puzzle text or your inputs.

The text I get, but the inputs? Well, I will comply, since I am getting a very nice thing for (almost) free, so it is polite to respect the wishes here, but since I commit the inputs (you know, since I want to be able to run tests) into the repository, it is bit of a shame the repo must be private.

sizzzzlerz - 2 days ago

I had never heard of this before I saw something announcing this years adventure. It looked interesting so I gave it a try, doing 2024. I had a blast. In concept, its very similar to the Euler Project but oriented more towards programming rather than being heavily mathematical. Like Euler, the first part is typically trivial while part 2 can put the hammer down and make you think to devise an approach that can arrive at a solution in milliseconds rather than the death of the universe.

aadv1k - 2 days ago

Advent of code is such a fantastic event. I am honestly glad it's 12 days this year, primarily because I would only ever get to day 13 or 14 before it would take me an entire day to finish the puzzles! This would be my fourth year doing AoC. Looking forward to it :)

I plan on doing this year in C++ because I have never worked with it and AoC is always a good excuse to learn a new language. My college exams just got over, so I have a ton of free time.

Previous attempts:

- in Lua https://github.com/Aadv1k/AdventOfLua2021

- in C https://github.com/Aadv1k/AdventOfC2022

- in Go https://github.com/Aadv1k/AdventOfGo2023

really hope I can get all the stars this time...Cheers, and Merry Cristmas!

d_watt - 2 days ago

Looks like after the AI automation rush last year, the leaderboard has been removed. Makes sense, a little sad that it was needed though.

jeroenhd - 2 days ago

I find it interesting how many sponsors run their own "advent of <x>". So far I've seen "cloud", "FPGA", and a "cyber security" one in the sponsors pages (although that last one is one I remember from last year).

I'm also surprised there are a few Dutch language sponsors. Do these show up for everyone or is there some kind of region filtering applied to the sponsors shown?

encomiast - 2 days ago

A little sad that there are fewer puzzles. But also a glad that I'll see my wife and maybe even go outside during the second half of December this year.

mattbillenstein - 2 days ago

I've done all the years and all the problems.

The part I enjoy the most is after figuring out a solution for myself is seeing what others did on Reddit or among a small group of friends who also does it. We often have slightly different solutions or realize one of our solutions worked "by accident" ignoring some side case that didn't appear in our particular input. That's really the fun of it imho.

singron - 2 days ago

BTW the page mentions Alternate Styles, which is an obscure feature in firefox (View -> Page Styles). If you try it out, you will probably run into [0] and not be able to reset the style. The workaround is to open the page in a different tab, which will go back to the default style.

0: https://bugzilla.mozilla.org/show_bug.cgi?id=1943796

bigell - 2 days ago

I love advent of code, and I look forward to it every year!

I've never stressed out about the leaderboard. Ive always taken it as an opportunity to learn a new language, or brush up on my skills.

In my day-to-day job, I rarely need to bootstrap a project from scratch, implement a depth first search of a graph, or experiment with new language features.

It's for reasons like these that I look forward to this every year. For me it's a great chance to sharpen the tools in my toolbox.

deergomoo - 2 days ago

> You don't need a computer science background to participate - just a little programming knowledge and some problem solving skills will get you pretty far.

Every time I see this I wonder how many amateur/hobbyist programmers it sets up for disappointment. Unless your definition of “pretty far” is “a small number of the part ones”, it’s simply not true.