Advent of Code 2025

https://adventofcode.com/2025/about

by vismit2000 • 8 months ago

1243 397 8 months ago

adventofcode.com

mynameismon• 8 months ago

Is it just me, or does it seem to be temporarily down?

retsibsi2• 8 months ago

It's up for me (but the first puzzle won't be available until 15 hours from now).

rdos• 8 months ago

It won't load for me right now

zwnow3• 8 months ago

Should I use AI to solve Advent of Code puzzles? No. If you send a friend to the gym on your behalf, would you expect to get stronger? Advent of Code puzzles are designed to be interesting for humans to solve - no consideration is made for whether AI can or cannot solve a puzzle. If you want practice prompting an AI, there are almost certainly better exercises elsewhere designed with that in mind.

And yet I expect the whole leaderboard to be full of AI submissions...

Edit: No leaderboard this year, nice!

stOneskull4• 8 months ago

i don't think there is a global leaderboard this year. just private ones.

retsibsi2• 8 months ago

Not this time:

The global leaderboard was one of the largest sources of stress for me, for the infrastructure, and for many users. People took things too seriously, going way outside the spirit of the contest; some people even resorted to things like DDoS attacks. Many people incorrectly concluded that they were somehow worse programmers because their own times didn't compare. What started as a fun feature in 2015 became an ever-growing problem, and so, after ten years of Advent of Code, I removed the global leaderboard.

KolmogorovComp• 8 months ago

And yet I expect the whole leaderboard to be full of AI submissions...

There will be no global leaderboard this year.

Cthulhu_• 8 months ago

I mean they're great programming tests, for both people and AI I'd argue - like, it'd be impressive if an AI can come up with a solution in short order, especially with minimal help / prompting / steering. But it wouldn't be a personal achievement, and if it was a competition I'd label it as cheating.

chongli2• 8 months ago

I am so glad there is no leaderboard this year. Making it a competition really is against the spirit of advent calendars in general. It’s also not a fair competition by default simply due to the issue of time zones and people’s life schedules not revolving around it.

There are plenty of programming competitions and hackathons out there. Let this one simply be a celebration of learning and the enjoyment of problem solving.

zwnow3• 8 months ago

Yea fully agree. The leaderboards always made me feel bad.

amitav1• 8 months ago

I agree with the first point but the second point feels irrelevant. Yeah, people's life schedules don't revolve around it, but that doesn't mean shouldn't make iy a competition. Most people who play on chess.com don't have lives that revolve around it, but that doesn't mean that chess.com should abolish Elo rankings.

losvedir2• 8 months ago

Depends how you look at it. Some of my colleagues rave about Claude Code, so I was thinking about trying it out on these puzzles. In that sense it is "going to the gym", just for a different thing. Since I do AoC every year, I feel like it'll give me a good feel for Claude Code compared to my baseline. And it's not just "prompting", but figuring out a workflow with tests and brainstorming and iteration and all that. I guess if the LLM can just one-shot every puzzle that's less interesting, but I suppose it would be good to know it can do that...

zwnow3• 8 months ago

It 100% can do that. LLMs are trained on an unfathomable amount of data. Every AoC puzzle can be solved by identifying the algorithm behind it. Its Leetcode in a friendlier and more festive spirit.

d_watt• 8 months 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.

ellisv• 8 months ago

I never liked the global leaderboard since I was usually asleep when the puzzles were released. I likely never would have had a competitive time anyway.

Jare• 8 months ago

I never had any hope or interest to compete in the leaderboard, but I found it fun to check it out, see times, time differences ("omg 1 min for part 1 and 6 for part 2"), lookup the names of the leaders to check if they have something public about their solutions, etc. One time I even ran into the name of an old friend so it was a good excuse to say hi.

Booleans• 8 months ago

I believe that Everybody Codes has a leaderboard where it starts counting from when you first open the puzzle. So if you're looking for coding puzzles with a leaderboard that one would be fair for you.

https://everybody.codes/events

PaulRobinson• 8 months 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.

f1shy4• 8 months ago

While is „only“ 12 days, are like 24 challenges. As no leaderboard is there, and I do it for fun, i will do it in 24 days.

tclancy• 8 months ago

Same. I usually try to use it as the "real-world problem" I need for learning a new language. Is there anywhere that people have starter advice/ templates for various languages? I'd love to know

- install like this

- initialize a directory with this command

- here are the VSCode extensions (or whatever IDE) that are the bare minimum for the language

- here's the command for running tests

eichin• 8 months ago

That sounds healthy! But I would note that there's been interesting community discussions on reddit in past years, and I've gotten caught up in the "finish faster so I can go join the reddit discussion without spoilers". It turns out you can have amazing in-jokes about software puzzles and ascii art - but it also taught me in a very visceral way that even for "little" problems, building a visualizer (or making sure your data structures are easy-to-visualize) is startlingly helpful... also that it's nice to have people to commiserate with who got stuck in the same garden path/rathole that you did.

volemo• 8 months ago

Yep, I don't really understand why the author didn't make it one per day for 24 days. Am I missing something obvious?

jakeydus• 8 months ago

I think I’ll set up a local leaderboard with friends this year. I was never going to make it to the global board anyway but it is sad to see it go away.

doublerabbit2• 8 months ago

And this is how I know I am not a developer/programmer. I have no urge or interest in such event.

skywhopper• 8 months ago

Why post, then? No one cares about your lack of interest.

unkulunkulu• 8 months ago

I wonder how this is the most straightforward way to know that?

onion2k2• 8 months ago

Your logic is flawed. You can be a developer and not be interested in AoC. Not being interested in AoC only shows you're not interested in AoC.

coolThingsFirst• 8 months ago

It's all marketing, I can sell this to you and convert you.

Thing is it may have some interesting challenges, I too, wouldn't want to solve some insane string parsing problem with no interesting idea behind it. For today's problem, I did the naive version and it worked. The modular version created some issues with some corner cases.

There should be more events like AoC. Self-contained problems are very educational.

forty• 8 months ago

The "only" 12 days might be disappointing (but totally understandable), however I won't mourn the global leaderboard which always felt pointless to me (even without the llm, the fact that it depends on what time you did solved problems really made it impractical for most people to actually compete). Private leaderboards with people on your timezone are much nicer.

mattbillenstein3• 8 months ago

The global leaderboard was a great way to find really crazy good people and solutions however - I picked through a couple of these guys solutions and learned a few things. One guy had even written his own special purpose language mainly to make AoC problems fast - he was of course a compilers guy.

ryandv5• 8 months ago

the global leaderboard had to be pulled.

Frankly I'm better off with it being this way instead of the sweaty cupstacking LLM% speedrun it became as it gained popularity.

lencastre3• 8 months ago

how else to try it? only for shits and giggles, there is enough fake virtual internet pointz as is

qsort2• 8 months ago

I'm actually pleasantly surprised to see a 2025 edition, last year being the 10th anniversary and the LLM situation with the leaderboard were solid indications that it would have been a great time to wrap it up and let somebody else carry the torch.

It's only going to be 12 problems rather than 24 this year and there isn't going to be a gloabl leaderboard, but I'm still glad we get to take part in this fun Christmas season tradition, and I'm thankful for all those who put in their free time so that we can get to enjoy the problems. It's probably an unpopular stance, but I've never done Advent of Code for the competitive aspect, I've always just enjoyed the puzzles, so as far as I'm concerned nothing was really lost.

squigz3• 8 months ago

It's really disheartening that the culture has changed so much someone would think doing AoC puzzles just for the fun of it is an unpopular stance :(

Doing things for the fun of it, for curiosity's sake, for the thrill of solving a fun problem - that's very much alive, don't worry!

Waterluvian2• 8 months ago

Eliminating the leaderboard might help. By measuring it as a race, it becomes a race, and now the goal is the metric.

Maybe just have a cool advent calendar thingy like a digital tree that gains an ornament for each day you complete. Each ornament can be themed for each puzzle.

Of course I hope it goes without saying that the creator(s) can do it however they want and we’re nothing but richer for it existing.

jerpint• 8 months ago

I did a post [0] about this last year, and vanilla LLMs didn’t do nearly as well as I’d expected on advent of code, though I’d be curious to try this again with Claude code and codex

[0] https://www.jerpint.io/blog/2024-12-30-advent-of-code-llms/

the_duke2• 8 months ago

LLMs, and especially coding focused models, have come a very long way in the past year.

The difference when working on larger tasks that require reasoning is night and day.

In theory it would be very interesting to go back and retry the 2024 tasks, but those will likely have ended up in the training data by now...

randomifcpfan• 8 months ago

Current frontier agents can one shot solve all 2024 AoC puzzles, just by pasting in the puzzle description and the input data.

From watching them work, they read the spec, write the code, run it on the examples, refine the code until it passes, and so on.

But we can’t tell whether the puzzle solutions are in the training data.

I’m looking forward to seeing how well current agents perform on 2025’s puzzles.

Aurornis3• 8 months ago

A couple of the Slack/Discord groups I’m in do a local leaderboard with friends. It’s fun to do with a trusted group of people who are all in it for fun.

qsort2• 8 months ago

I'm also in a few local leaderboards, but I'm not "really" competing, it's more of a fun group thing.

Premises:

(i) I love Advent of Code and I'm grateful for its continuing existence in whatever form its creators feel like it's best for themselves and the community;

(ii) none of what follows is a request, let alone a demand, for anything to change;

(iii) what follows is just the opinion of some random guy on the Internet.

I have a lot of experience with competitions (although more on the math side than on the programming side), and I've been involved essentially since I was in high school, as a contestant, coach, problem writer, organizer, moving tables, etc. In my opinion Advent of Code simply isn't a good competition:

- You need to be available for many days in a row for 15 minutes at a very specific time.

- The problems are too easy.

- There is no time/memory check: you can write ooga-booga code and still pass.

- Some problems require weird parsing.

- Some problems are pure implementation challenges.

- The AoC guy loves recursive descent parsers way too much.

- A lot of problems are underspecified (you can make assumptions not in the problem statement).

- Some problems require manual input inspection.

To reiterate once again: I am not saying that any of this needs to change. Many of the things that make Advent of Code a bad competition are what make it an excellent, fun, memorable "Christmas group thing". Coming back every day creates community and gives people time to discuss the problems. Problems being easy and not requiring specific time complexities to be accepted make the event accessible. Problems not being straight algorithmic challenges add welcome variety.

I like doing competitions but Advent of Code has always felt more like a cozy problem solving festival, I never cared too much for the competitive aspect, local or global.

scuff3d• 8 months ago

I know some folks were disappointed with their being 12 puzzles instead of 24 this year, but I never have time to finish anyway so it makes no difference to me lol

I'm just glad they're keeping this going.

jbv027• 8 months ago

Exactly. I have always taken AoC as fun and time to learn. But there is so much going on during December and I do not enjoy doing more than one puzzle a day (it feels like hard work instead of fun). I usually spend time on weekends with kids and family and I am not willing to solve more puzzles during week days so I am falling behind all the time. My plan was always to finish last year puzzles to enjoy more interesting ones but it always felt wrong. So I hope I will have time to finish everything this year :-) But I feel pain from people with enough free time to go full on. I would love to be one of them but there is so much going on everywhere that I have to split my time. Sorry programming world and especially computers :-D

integralid2• 8 months ago

It's probably an unpopular stance, but I've never done Advent of Code for the competitive aspect

Is this an unpopular stance? Out of a dozen people I know that did/do AoC every year, only one was trying to compete. Everyone else did it for fun, to learn new languages or concepts, to practice coding, etc.

Maybe it helps that, because of timezones, in Europe you need to be really dedicated to play for a win.

Jtsummers5• 8 months ago

Is this an unpopular stance?

No, it's not. At most 200 people could end up on the global leaderboard, and there are tens of thousands of people who participate most days (though it drops off by the end, it's over 100k reliably for the first day). The vast majority of participants are not there for the leaderboard. If you care about being competing, there are always private leaderboards.

encomiast2• 8 months 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.

returningfory2• 8 months ago

I hope your wife is also glad!

permalac• 8 months ago

Does anyone know about any good sysadmin advent?

ahoka4• 8 months ago

I propose Advent of Outage: just pull a random plug in the server room every day.

tgv5• 8 months ago

How about something like

    while [1]; do kill -9 $((rnd * 100000)); sleep 5; end

Probably needs some external tool for the rnd function.

On a serious note, I just saw this: https://linuxupskillchallenge.org

fduran2• 8 months ago

I haven't set up an advent event (maybe I should) but you can do yourself a challenge a day from SadServers.com

fduran2• 8 months ago

https://sadservers.com/advent

fainpul2• 8 months 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).

f1shy4• 8 months ago

I’ve been doing them is JS and Common Lisp. I recommend the problems to help learning new languages.

StopDisinfo910• 8 months ago

I respect the effort going into making Advent of Code but with the very heavy emphasis on string parsing, I'm not convinced it's a good way to learn most languages.

Most problems are 80%-90% massaging the input with a little data modeling which you might have to rethink for the second part and algorithms used to play a significant role only in the last few days.

That heavily favours languages which make manipulating string effortless and have very permissive data structures like Python dict or JS objects.

4pkjai• 8 months ago

Kotlin, because it’s a language I like

jpgvm• 8 months ago

IMO it's maybe the best suited language to AoC. You can write it even faster than Python, has a very terse syntax and great numerical performance for the few challenges where that matters.

speed_spread• 8 months ago

Modern straight Java works just as well.

encomiast2• 8 months ago

It was mind-boggling to see SQL solutions last year: https://news.ycombinator.com/item?id=42577736

JokerDan• 8 months ago

This is what is great about it, the community posting hyper-creative (sometimes cursed) solutions for fun! I usually use AoC to try out a new language and that has been fun for me over the years.

shakna• 8 months ago

I've always done it in a Scheme. Generally to learn a new compiler and its quirks.

Scheme is fairly well suited to both general programming, and abstract math, which tends to be a good fit for AoC.

fainpul2• 8 months ago

For some grid based problems, I think spreadsheets are very powerful and under-appreciated.

The spatial and functional problem solving makes it easy to reason about how a single cell is calculated. Then simply apply that logic to all cells to come up with the solution.

sunrunner3• 8 months ago

My favourite "non-mainstream" languages are, depending on my mood at the time, either:

- Array languages such as K or Uiua. Why they're good for AoC: Great for showing off, no-one else can read your solution (including yourself a few days later), good for earlier days that might not feel as challenging

- Raw-dogging it by creating a Game Boy ROM in ASM (for the Game Boy's 'Z80-ish' Sharp LR35902). Why it's good for AoC: All of the above, you've got too much free time on your hands

Just kidding, I use Clojure or Python, and you can pry itertools from my cold, dead hands.

infamousclyde• 8 months ago

I’ve always used AoC as my jump-off point for new languages. I was thinking about using Gleam this year! I wish I had more profound reasons, but the pipeline syntax is intriguing and I just want to give it a whirl.

ceautery• 8 months ago

That's a perfectly valid reason.

I tried AoC out one year with the Wolfram language, which sounds insane now, but back then it was just a "seemed like the thing to do at the time" and I'm glad I did it.

tgv5• 8 months ago

I started only last year, to learn a bit of Ada. Doing SPARK this year. That has been on my TOLEARN list for a long time. Should be interesting.

jlouis2• 8 months ago

Go is strong. You get something where writing a solution doesn't take too much time, you get a type system, you can brute-force problems, and the usual mind-numbing boring data-manipulation handling fits well into the standard tools.

OCaml is strong too. Stellar type system, fast execution and sane semantics unlike like 99% of all programming languages. If you want to create elegant solutions to problems, it's a good language.

For both, I recommend coming prepared. Set up a scaffold and create a toolbox which matches the typical problems you see in AoC. There's bound to be a 2d grid among the problems, and you need an implementation. If it can handle out-of-bounds access gracefully, things are often much easier, and so on. You don't want to hammer the head against the wall not solving the problem, but solving parsing problems. Having a combinator-parser library already in the project will help, for instance.

sunrunner3• 8 months ago

For both, I recommend coming prepared.

Any recommendations for Go? Traditionally I've gone for Python or Clojure with an 'only builtins or things I add myself' approach (e.g. no NetworkX), but I've been keen to try doing a year in Go however was a bit put off by the verbosity of the parsing and not wanting to get caught spending more time futzing with input lines and err.

Naturally later problems get more puzzle-heavy so the ratio of input-handling to puzzle-solving code changes, but it seemed a bit off putting for early days, and while I like a builtins-only approach it seems like the input handling would really benefit from a 'parse don't validate' type approach (goparsec?).

bashkiddie• 8 months ago

Go is strong.

How do you parse the puzzle input into a data structure of your choice?

riffraff• 8 months ago

I usually do it with ruby with is well suite just like python, but last year I did it with Elixir.

I think it lends itself very well to the problem set, the language is very expressive, the standard library is extensive, you can solve most things functionally with no state at all. Yet, you can use global state for things like memoization without having to rewrite all your functions so that's nice too.

marc_omorain• 8 months ago

Clojure works really well for AOC.

A lot of the problems involve manipulating sets and maps, which Clojure makes really straightforward.

Barrin922• 8 months ago

I'll second Clojure not just for the data structures but also because of the high level functions the standard library ships with.

Things like `partition`, `cycle` or `repeat` have come in so handy when working with segments of lists or the Conway's Game-of-Life type puzzles.

bhollan• 8 months ago

I used MATLAB last year while I was re-learning it for work. It did okay, but we didn't have a license for the Image Processing Toolbox, which has a boatload of tools for the grid based problems.

rootnod33• 8 months ago

My personal choice is always Common Lisp. Absolute swiss army knife.

tmtvl• 8 months ago

With both AoC and Project Euler I like seeing how fast I can get my solution to run with SBCL. Finding all palindromic primes below a million in less than a second is pretty neat.

WJW3• 8 months ago

I like to use Haskell, because parser combinators usually make the input parsing aspect of the puzzles extremely straightforward. In addition, the focus of the language on laziness and recursion can lead to some very concise yet idiomatic solutions.

Example: find the first example for when this "game of life" variant has more than 1000 cells in the "alive" state.

Solution: generate infinite list of all states and iterate over them until you find one with >= 1000 alive cells.

    let allStates = iterate nextState beginState # infinite list of consecutive solutions
    let solution = head $ dropWhile (\currentState -> numAliveCells currentState < 1000) allStates

lkuty• 8 months ago

Do you plan to share your solutions on Github or something similar ?

jvuygbbkuurx• 8 months ago

Does this solution copy the state on each iteration?

taolson3• 8 months ago

Yes, there are some cool solutions using laziness that aren't immediately obvious. For example, in 2015 and 2024 there were problems involving circuits of gates that were elegantly solved using the Löb function:

https://github.com/quchen/articles/blob/master/loeb-moeb.md

sevenseacat2• 8 months ago

I've been using Elixir since day one, and it works pretty well :)

aloisdg• 8 months ago

I plan to do it in elixir too this year :)

nemo16182• 8 months ago

I made my own, with a Haskell+Bash flavor and a REPL that reloads with each keystroke: https://www.youtube.com/watch?v=r99-nzGDapg

This year I've been working on a bytecode compiler for it, which has been a nice challenge. :)

When I want to get on the leaderboard, though, I use Go. I definitely felt a bit handicapped by the extra typing and lack of 'import solution' (compared to Python), but with an ever-growing 'utils' package and Go's fast compile times, you can still be competitive. I am very proud of my 1st place finish on Day 19 2022, and I credit it to Go's execution speed, which made my brute-force-with-heuristics approach just fast enough to be viable.

taolson3• 8 months ago

I made my own, with a Haskell+Bash flavor and a REPL that reloads with each keystroke

That was impressive! Do you have a public repo with your language, anywhere?

natrys• 8 months ago

I am going to try and stick with Prolog as much as I can this year. Plenty of problems involve a lot of parsing and searching, both could be expressed declaratively in Prolog and it just works (though you do have to keep the execution model in mind).

keithlfrost• 8 months ago

Elixir Livebook is my tool of choice for Advent of Code. The language is well-suited for the puzzles, I can write some Markdown if I need to record some algebra or my thought process, the notebook format serves as a REPL for instant code testing, and if the solution doesn't fit neatly into an executable form, I can write up my manual steps as well.

incognito124• 8 months ago

If I remember correctly, one of the competitive programming experts from the global leaderboard made his own language, specifically tailored to help solve AoC problems:

https://github.com/betaveros/noulith

wging2• 8 months ago

Yes (or so I thought too!), but apparently no: https://blog.vero.site/post/noulith

(post title: "Designing a Programming Language to Speedrun Advent of Code", but starts off "The title is clickbait. I did not design and implement a programming language for the sole or even primary purpose of leaderboarding on Advent of Code. It just turned out that the programming language I was working on fit the task remarkably well.")

taolson3• 8 months ago

AoC has been a highlight of the season for me since the beginning in 2015. I experimented with many languages over the years, zeroing in on Haskell, then Miranda as my language of choice. Finally, I decided to write my own language to do AoC, and created Admiran (based upon Miranda and other lazy, pure, functional languages) with its own self-hosted compiler and library of functional data structures that are useful in AoC puzzles:

https://github.com/taolson/Admiran https://github.com/taolson/advent-of-code

mrkaye97• 8 months ago

I've been using Elixir, which has been wonderful, mostly because of how amazing the built in `Enum` library is for working on lists and maps (since the majority of AoC problems are list / map processing problems, at least for the first while)

cyberpunk• 8 months ago

Enum really does feel like a superpower sometimes. I’ll knock out some loop and then spend a few mins with h Enum.<tab> and realise it could’ve been one or two Enum functions.

yoyohello13• 8 months ago

Haskell is my favorite for advent of code. Finally give me an opportunity to think in a pure functional way.

matsemann3• 8 months ago

I use python at work but code these in kotlin. The stdlib for lists is very comprehensive, and the syntax is sweet. So easy to make a chain of map, filter and some reduction or nice util (foldr, zipwithnext, windowed etc). Flows very well with my thought process, where in python I feel list comprehensions are the wrong order, lambdas are weak etc.

I write most as pure functional/immutable code unless a problem calls for speed. And with extension functions I've made over the years and a small library (like 2d vectors or grid utils) it's quite nice to work with. Like, if I have a 2D list (List<List<E>>), and my 2d vec, like a = IntVec(5,3), I can do myList[a] and get the element due to an operator overload extension on list-lists.

and with my own utils and extension functions added over years of competitive programming (like it's very fluent

vharuck• 8 months ago

I've done some of the problems in R. Vectorized-by-default can avoid a lot of boilerplate. And for problems that aren't in R's happy path, I learn how to optimize in the language. And then I try to make those optimizations non-hideous to read.

ashdnazg• 8 months ago

My wife did one of the years in Matlab. Some of the problems translate very nicely into vectors and matrices.

azkalam2• 8 months ago

Terse languages with great collection functions in the standard libraries and tail call optimization. Haskell, OCaml, F# ...

yxhuvud• 8 months ago

Crystal. Expressiveness and get-shit-done ability similar to the one of Ruby while being way faster in execution.

Alex_L_Wood• 8 months ago

Not sure if Kotlin is non-mainstream, but being able to use the vast Java libraries choice and a much nicer syntax are great boons.

auxym• 8 months ago

I've had a lot of fun using Nim for AOC for many years. Once you're familiar with the language and std lib, its almost as fast to write as python, but much faster (Nim compiles to C, which then gets compiled to your executable). This means that sometimes, if your solution isn't perfect in terms of algorithmic complexity, waiting a few minutes can still save you (waiting 5 mins for your slow Nim code is OK, waiting 5 hours for your slow Python isn't really, for me). Of course all problems have a solution that can run in seconds even in Python, but sometimes it's not the one I figure out first try.

Downsides: The debugging situation is pretty bad (hope you like printf debugging), smaller community means smaller package ecosystem and fewer reference solutions to look up if you're stuck or looking for interesting alternative ideas after solving a problem on your own, but there's still quality stuff out there.

Though personally I'm thinking of trying Go this year, just for fun and learning something new.

Edit: also a static type system can save you from a few stupid bugs that you then spend 15 minutes tracking down because you added a "15" to your list without converting it to an int first or something like that.

AstroBen• 8 months ago

This question is really confusing to me because the point of AoC is the fun and experience of it

So.. a language that you're interested in or like?

Reminds me of "gamers will optimize the fun out of a game"

I'm pretty clojure-curious so might mess around with doing it in that

andriamanitra• 8 months ago

I think Ruby is the ideal language for AoC:

* The expressive syntax helps keep the solutions short.

* It has extensive standard library with tons of handy methods for AoC style problems: Enumerable#each_cons, Enumerable#each_slice, Array#transpose, Array#permutation, ...

* The bundled "prime" gem (for generating primes, checking primality, and prime factorization) comes in handy for at least a few of problems each year.

* The tools for parsing inputs and string manipulation are a bit more ergonomic than what you get even in Python: first class regular expression syntax, String#scan, String#[], Regexp::union, ...

* You can easily build your solution step-by-step by chaining method calls. I would typically start with `p File.readlines("input.txt")` and keep executing the script after adding each new method call so I can inspect the intermediate results.

ilvez2• 8 months ago

Haven't used prime stuff, since not so versed in algorithms I guess, but other than that totally agree. So far have enjoyed it the most. Though I remember doing those really elongated Go solutions consisting of long for loops over and over... When they were ready and ran, they were very fast even with brute force solutions.

christophilus2• 8 months ago

I’d say Clojure because it has great data manipulation utilities baked into the standard library.

andrelaszlo• 8 months ago

I think Crystal, Nim, Julia and F# were my favorites from last year's AoC

I wrote a bit more about it here https://laszlo.nu/blog/advent-of-code-2024.html

AoC is a great opportunity for exploring languages!

makerofthings2• 8 months ago

Another vote for Haskell. It’s fun and the parsing bit is easy. I do struggle with some of the 2d map style questions which are simpler in a mutable 2d array in c++. It’s sometimes hard to write throwaway code in Haskell!

tonyedgecombe• 8 months ago

I think that whatever you know well is the best choice.

nedt• 8 months ago

The language doesn't really matter much. I think I keep using PHP as in the years before.

jcadam• 8 months ago

I tried to do it in emacs lisp one year. Made it about halfway :)

alexfoo11• 8 months ago

Perl is my starting point.

It has many of the required structures (hashes/maps, ad hoc structs, etc) and is great for knocking up a rough and ready prototype of something. It's also quick to write (but often unforgiving).

I can also produce a solution for pretty much every problem in AoC without needing to download a single separate Perl module.

On the negative side there are copious footguns available in Perl.

(Note that if I knew Python as well as I knew Perl I'd almost certainly use Python as a starting point.)

I also try and produce a Go and a C solution for each day too:

* The Go solution is generally a rewrite of the initial Perl solution but doing things "properly" and correcting a lot of the assumptions and hacks that I made in the Perl code. Plus some of those new fangled "test" things.

* The C solution is a useful reminder of how much "fun" things can be in a language that lacks built-in structures like hashes/maps, etc.

yifanl• 8 months ago

I believe Eric has said he always makes his first solutions with Perl.

RobKohr• 8 months ago

I have been learning lua to do a VR game in lovr, so I'll probably use that to get sharper with it.

crystal_revenge4• 8 months ago

For me (and most of my friends/coworkers) the point of AoC was to write in some language that you always wanted to learn but never had the chance. The AoC problems tend to be excellent material for a crash course in a new PL because they cover a range of common programming tasks.

Historically good candidates are:

- Rust (despite it's popularity, I know a lot of devs who haven't had time to play with it).

- Haskell (though today I'd try Lean4)

- Racket/Common Lisp/Other scheme lisp you haven't tried

- Erlang/Elixir (probably my choice this year)

- Prolog

Especially for those langs that people typically dabble in but never get a change to write non-trivial software in (Haskell, Prolog, Racket) AoC is fantastic for really getting a feel for the language.

ngrislain3• 8 months ago

Yes, this year I'm going for Lean 4: https://github.com/ngrislain/lean-adventofcode-2025

It's a great language. It's dependent-types / theorem-proving-oriented type-system combined with AI assistants makes it the language of the future IMO.

reddit_clone• 8 months ago

I have used Raku (Perl 6) with good results.

Common Lisp. Using 'iterate' package almost feels like cheating.

I have done half a year in (noob level) Haskell long ago. But can't find the code any more.

Most mind blowing thing for me was looking at someone's solutions in APL!

bombcar• 8 months ago

The only way to win is with Brainfuck.

Or MUMPS.

ghewgill• 8 months ago

I've done AoC on what I call "hard mode", where I do the solutions in a language I designed and implemented myself. It's not because the language is particularly suited to AoC in any particular way, but it gives me confidence that my language can be used to solve real problems.

Neon Language: https://neon-lang.dev/ Some previous AoC solutions: https://github.com/ghewgill/adventofcode

paddim8• 8 months ago

I used my homemade shell language last year, called elk shell. It worked surprisingly well, better than other languages I've tried, because unlike other shell languages it is just a regular general purpose scripting language with a standard library that can also run programs with the same syntax as function calls.

SilverSlash2• 8 months ago

Is Rust still "non-mainstream"? Because it's extremely well suited for AoC. The ergonomics of a high-level language with the performance of C++.

fragmede• 8 months ago

The ergonomics of a high-level language

Is there a way to drop into a repl like with python and pdb.set_trace()? I couldn't find one last time I played around with Rust.

radiator• 8 months ago

A new language every year. A language I had intended to learn. Using a different programming paradigm, or a paradigm which I have not used recently.

tomjen3• 8 months ago

With AoC I think that its fine to pick a language that is not at all suited for the challenge. That can be half the fun.

I saw someone one Twitter use Excel.

talideon3• 8 months ago

OCaml. There's just enough in the standard library to cover what you need for everything, for any non-trivial parsing tasks, there's a parser generator and lexer generator bundled, and if you want to pull in extra support libraries so you're not looking to implement, say, a trie from scratch.

thomasjb• 8 months ago

C, because it makes every problem into a memory management problem, which is good for you in an 'eat your vegetables' sort of way. It's also the starting point for a lot of other programming languages and related things like HDLs, which is helpful to me.

I'm plodding my way through the 2015 challenge here: https://git.thomasballantine.com/thomasballantine/Advent_of_... , it's really sharpened me up on a number of points.

queuebert3• 8 months ago

My favorite non-mainstream language for competitions like this and Project Euler is Julia. The startup time is not a factor, and the ability to use UTF-8 symbols as variables makes the code more mathematical.

nurettin• 8 months ago

If it is not solvable with a Ruby one-liner, it is not a well defined problem.

the_duke2• 8 months ago

I use AoC as a chance to try a new language every year.

In the past I used it to try out Swift, J, R, ...

GuB-42• 8 months ago

I haven't tried it, but I may consider Raku (ex Perl 6). It is very expressive and loaded with features.

AoC-like problems are well suited to quick and dirty languages with lots of builtin features, the code doesn't have to be maintained and it is small enough to not require organization.

lencastre3• 8 months ago

I solved day 1 with ms excel formulas :-) but from day 2 onwards I switched to python, the formula constraints in ms excel are a pain and I am not so masochistic

Archit3ch• 8 months ago

Anyone doing this in OpenGL?

legends2k2• 8 months ago

I'm not sure I understand this. Most puzzles are number-crunching but very little to do with graphics (maybe one or two), so no usually OpenGL isn't used AFAIK.

Of course, folks may use it to visualise the puzzles but not to solve them.

ben-schaaf• 8 months ago

You definitely could do it all in shaders. People have done crazier things.

holyknight• 8 months ago

I never understood the craze for "Advent of code". Already at this time of the year the last thing I want to do is code even more.

ls-a5• 8 months ago

I agree. Didn't these puzzles ruin interviewing for many years now. AI came along and they're still doing it. Some things will needlessly drag on before they die I guess

MattRix• 8 months ago

How do they ruin interviewing? The whole point of these puzzles is that they’re meant to be fun to solve, not a means to an end, but enjoyable for what they are.

legends2k2• 8 months ago

By the same token, AI came along and we all still have intelligence, needless, eh? I mean people reading and writing stuff has nothing to do with AI. I don't see how some people see everything as a zero-sum game.

phartenfeller• 8 months ago

Well some people like to code and logic puzzles. And especially as it is in its raw form where you can forget all the noise you encounter while coding professionally with many hoops and responsibilities.

sumeno• 8 months ago

People like different things

ls-a5• 8 months ago

and dislike different things

wkjagt• 8 months ago

I code for fun, even in December.

kylegalbraith• 8 months ago

Excited to see AOC back and I think it was a solid idea to get rid of the global leaderboard.

We (Depot) are sponsoring this year and have a private leaderboard [0]. We’re donating $1k/each for the top five finishers to a charity of their choice.

[0] https://depot.dev/events/advent-of-code-2025

Arainach• 8 months ago

Isn't a publicly advertised private leaderboard - especially with cash prizes - against the new guidance? Certainly the spirit of the guidance.

What happened to the global leaderboard? The global leaderboard was one of the largest sources of stress for me, for the infrastructure, and for many users. People took things too seriously, going way outside the spirit of the contest; some people even resorted to things like DDoS attacks. Many people incorrectly concluded that they were somehow worse programmers because their own times didn't compare. What started as a fun feature in 2015 became an ever-growing problem, and so, after ten years of Advent of Code, I removed the global leaderboard. (However, I've made it so you can share a read-only view of your private leaderboard. *Please don't use this feature or data to create a "new" global leaderboard.*)

ahoka4• 8 months ago

This kind of crap is the reason we can’t just enjoy an AoC anymore.

codr72• 8 months ago

Agreed, reward participation, not results.

stOneskull4• 8 months ago

i don't think it should be a charity of their choice. i think it should have to be one of the top 5 most reputable charities in the world, like doctors without borders or salvation army.

IsraelAfangideh• 8 months ago

This will be my first one! My primary languages are Typescript and Java. Looking forward to it!

jeroenhd3• 8 months ago

While part of the fun is doing the daily tasks with your friends, you can still access the previous years and their challenges if you want to continue after advent!

gray_-_wolf2• 8 months 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.

sevenseacat2• 8 months ago

I use git-crypt to encrypt the inputs in my public repo https://www.agwa.name/projects/git-crypt/ :)

rawling2• 8 months ago

I don't push my solutions publicly, but I made an input downloader so you can input your cookie from your browser and load (and cache) the inputs rather than commit them.

gerikson2• 8 months ago

If enough inputs are available online, someone can presumably collect them and clone the entire project without having access to the puzzle input generation code, which is the "secret sauce" of the project.

losvedir2• 8 months ago

Are you saying that we all have different inputs? I've never actually checked that, but I don't think it's true. My colleagues have gotten stuck in the same places and have mentioned aspects of puzzles and input characteristics and never spoken past each other. I feel like if we had different inputs we'd have noticed by now.

yesbabyyes2• 8 months ago

This is not surprising at all, to me. Just commit the example input and write your test cases against that. In a nicely structured solution, this works beautifully with example style tests, like python or rust doctests, or even running jsdoc @example stanzas as tests with e.g. the @linus/testy module.

gray_-_wolf2• 8 months ago

Just commit the example input

The example input(s) is part of the "text", and so committing it is also not allowed. I guess I could craft my own example inputs and commit those, but that exceed the level of effort I am willing to expend trying to publish repository no one will likely ever read. :)

MyOutfitIsVague• 8 months ago

I make my code public, and keep my inputs in a private submodule.

jedimastert• 8 months ago

The inputs are part of the validation that you did the question, so they're kind of a secret.

12345hn6789• 8 months ago

It is quite odd to call this advent when it ends halfway into the month rather than on Christmas. But I will have fun doing them either way

smokel2• 8 months ago

It may have made more sense to start on Christmas Day, matching the Twelve Days of Christmas [1].

[1] https://en.wikipedia.org/wiki/Twelve_Days_of_Christmas

tgv5• 8 months ago

I think there's a problem every other day, so it's 1, 3, ..., 23.

alexfoo11• 8 months ago

No, the puzzles are every day from the 1st to the 12th inclusive.

From https://adventofcode.com/2025/about:

" Why did the number of days per event change? It takes a ton of my free time every year to run Advent of Code, and building the puzzles accounts for the majority of that time. After keeping a consistent schedule for ten years(!), I needed a change. The puzzles still start on December 1st so that the day numbers make sense (Day 1 = Dec 1), and puzzles come out every day (ending mid-December). "

noirscape• 8 months 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.

phatfish• 8 months ago

LLMs spoiled it, but it was fun to see the genuine top times. Watching competitive coders solve in real time is interesting (Youtube videos), and i wouldn't have discovered these without the leader board.

eshse• 8 months ago

I live in Sweden nowadays (UTC+1) and it starts at 6am so last year I woke up at 5:30, grabbed a coffee, and gave it a go.

Got nowhere near the leaderboard times so gave up after four days!

thedavibob• 8 months ago

Yes: I'd argue that the timings actually work/worked better for Western Europe than the USA, I personally preferred doing the puzzle at 5am (UK) than the midnight equivalent, as I could finish before work (on a good day).

Nearly scratched a decent ranking once only, top 300 or so.

phplovesong• 8 months ago

I usually use multiple languages. Ocaml anf Go are always a pick. This year i think i want to try Gleam, and Haxe too.

georgehotz2• 8 months ago

I support the no global leaderboard. I was in 7th place last year but quickly got bored maintaining the aggressive AI pipeline required to achieve that. If I wanted to maintain pipelines I'd just do work, and there will never be a good way to prevent people from using AI like this. Advent of Code should be fun, thank you for continuing to do it. I'm looking forward to casually playing this year!

minitech2• 8 months ago

It was pretty boring trying to place against aggressive AI pipelines like yours throughout the explicit requests not to use them[1]. I’m sorry to hear it became boring for you too.

[1] https://web.archive.org/web/20241201070128/https://adventofc...

georgehotz2• 8 months ago

I mean, everyone else was using them too, how can you not? That was the name of the game if you wanted to be competitive in 2024. Not using them would be like trying to do competitive pro cycling without steroids, basically impossible.

karel-3d• 8 months ago

"It was boring to run a cycling contest on a motorbike."

Although there are now rumours of hidden motors in Tour de France bicycles. So, I guess it's the same.

makerofthings2• 8 months ago

The FAQ was pretty clear about not using AI to get on the leaderboard last year.

pred_• 8 months ago

So, publicly admitting that you broke the rules and are part of the reason we can't have nice things. Why?

hooverd• 8 months ago

this is why we can't have nice things

ahoka4• 8 months ago

Wow, you have some nerves.

bitbasher2• 8 months ago

I'd like to play, sadly you can't without logging in with google, github, etc.

Jtsummers5• 8 months ago

You can always create a throwaway account on one of those services. It's not that hard.

bitbasher2• 8 months ago

You could, but you shouldn't have to. If you want to sign up for XYZ, you need to sign up for BigCorp, you need to add your phone number to verify your account, etc.

No thanks.

HendrikHensen2• 8 months ago

The "etc" is pretty important here. You can log in using Reddit, and you can create a random throwaway Reddit account without filling in any other details (no email address or phone number required).

chucksmash• 8 months ago

I believe they no longer allow new accounts without an email address.

It used to be that reddit had a user creation screen that looked like you needed to input an email address, but you could actually just click "Next" to skip it.

The last time I had cause to make a reddit account, they no longer allowed this.

jeroenhd3• 8 months ago

Having done my own auth I get why they do it this way. LLMs are already a massive problem with AoC, I imagine an anonymous endpoint to validate solutions would be even worse.

Having done auth myself, I can also understand why auth is being externalised like this. The site was flooded with bots and scrapers long before LLMs gained relevance and adding all the CAPTCHAs and responding to the "why are you blocking my shady CGNAT ISP when I'm one of the good ones" complaints is just not worth it. Let some company with the right expertise deal with all of that bullshit.

I'd wish the site would have more login options, though. It's a tough nut to crack; pick a small, independent oauth login service not under control of a bit tech company and you're basically DDOSing their account creation page for all of December. Pick a big tech company and you're probably not gaining any new users. You can't do decentralized auth because then you're just doing authentication DDOS with extra steps.

If I didn't have a github account, I'd probably go with a throwaway reddit account to take part. Reddit doesn't really do the same type of tracking Twitter tries to do and it's probably the least privacy invasive of the bunch.

udev40963• 8 months ago

Agreed. I think having an option for codeberg would be great

quirino2• 8 months ago

Small anecdote:

In the IEEEXTREME university programming competition there are ~10k participating teams.

Our university has a quite strong Competitive Programming program and the best teams usually rank in the top 100. Last year a team ranked 30 and it's wasn't even our strongest team (which didn't participate)

This year none of our teams was able to get in the top 1000. I would estimate close to 99% of the teams in the Top 1000 were using LLMs.

Last year they didn't seem to help much, but this year they rendered the competition pointless.

I've read blogs/seen videos of people who got in the AOC global leaderboard last year without using LLMs, but I think this year it wouldn't be possible at all.

letmetweakit• 8 months ago

Man, those people using LLMs in competitive programming ... where's the fun in that? I don't get people for whom it's just about winning, I wish everyone would just have some basic form of dignity and respect.

jvanderbot2• 8 months ago

Yeah, it's like bringing a ~bike~ motorcycle to your marathon. But if you can get away with it, there will always be people doing it.

Imagine the shitshow that gaming would be without any kind of anti-cheat measures, and that's the state of competitive programming.

Ekaros• 8 months ago

Weirdly I feel lot more accepting of LLMs in this type of environment than in making actual products. Point is doing things fast and correct enough. So in someways LLM is just one more tool.

With products I want actual correctness. And not something thrown away.

evil-olive• 8 months ago

I don't get people for whom it's just about winning, I wish everyone would just have some basic form of dignity and respect.

reminds me of something I read in "I’m a high schooler. AI is demolishing my education." [0,1] emphasis added:

During my sophomore year, I participated in my school’s debate team. I was excited to have a space outside the classroom where creativity, critical thinking, and intellectual rigor were valued and sharpened. I love the rush of building arguments from scratch. ChatGPT was released back in 2022, when I was a freshman, but the debate team weathered that first year without being overly influenced by the technology—at least as far as I could tell. But soon, AI took hold there as well. Many students avoided the technology and still stand against it, but it was impossible to ignore what we saw at competitions: chatbots being used for research and to construct arguments between rounds.

high school debate used to be an extracurricular thing students could do for fun. now they're using chatbots in order to generate arguments that the students can just regurgitate.

the end state of this seems like a variation on Dead Internet Theory - Team A is arguing the "pro" side of some issue, Team B is arguing the "con" side, but it's just an LLM generating talking points for both sides and the humans acting as mouthpieces. it still looks like a "debate" to an outside observer, but all the critical thinking has been stripped away.

0: https://www.theatlantic.com/technology/archive/2025/09/high-...

1: https://archive.is/Lda1x

Aurornis3• 8 months ago

I’m a very casual gamer but even I run into obvious cheaters in any popular online game all the time.

Cheating is rampant anywhere there’s an online competition. The cheaters don’t care about respecting others, they get a thrill out of getting a lot of points against other people who are trying to compete.

Even in the real world, my runner friends always have stories about people getting caught cutting trails and all of the lengths their running organizations have to go through now to catch cheaters because it’s so common.

The thing about cheaters in a large competition is that it doesn’t take many to crowd out the leaderboard, because the leaderboard is where they get selected out. If there are 1000 teams competing and only 1% cheat, that 1% could still fill the top 10.

Isamu• 8 months ago

It can be a matter of values from your upbringing or immediate environment. There are plenty of places where they value the results, not the journey, and they think that people who avoid cheating are chumps. Think about that: you are in a situation where you just want to do things for fun but everyone around you will disrespect you for not taking the easy way out.

hoherd• 8 months ago

Yeah. I was happy to see this called out in their /about

Should I use AI to solve Advent of Code puzzles? No. If you send a friend to the gym on your behalf, would you expect to get stronger? Advent of Code puzzles are designed to be interesting for humans to solve - no consideration is made for whether AI can or cannot solve a puzzle. If you want practice prompting an AI, there are almost certainly better exercises elsewhere designed with that in mind.

zerr• 8 months ago

I believe the reason is that many still use CP for hiring, so people go into leetcode (or AdventOfCode) grind, sadly.

zulban• 8 months ago

It's a different kind of fun. Just like doing math problems on paper can be fun, or writing code to do the math can be fun, or getting AI to write the code to do the math can be fun.

They're just different types of fun. The problem is if one type of fun is ruined by another.

armchairhacker• 8 months ago

In 1997, Deep Blue beat Gary Kasparov, the world chess champion. Today, chess grandmasters stand no chance against Stockfish, a chess engine that can run on a cheap phone. Yet chess remains super popular and competitive today, and while there are occasional scandals, cheating seems to be mostly prevented.

I don’t see why competitive debate or programming would be different. (But I understand why a fair global leaderboard for AOC is no longer feasible).

ewidar• 8 months ago

Online chess competitions actually spend quite a lot on preventing cheating, and even then it's a common talking point.

matsemann3• 8 months ago

When I did competitions like these at uni (~10-15 years ago), we all used some thin-clients in the computer lab where the only webpages one could access were those allowed by the competition (mainly the submission portal). And then some admin/organizers would feed us and make sure people didn't cheat. Maybe we need to get back to that setup, heh.

quirino2• 8 months ago

Serious in-person competitions like ICPC are still effective against cheating. The first phase happens in a limited number of venues and the computers run a custom OS without internet access. There are many people watching so competitors don't user their phones, etc.

The Regional Finals and World Finals are in a single venue with a very controlled environment. Just like the IOI and other major competitions.

National High School Olympiads have been dealing with bigger issues because there are too many participants in the first few phases, and usually the schools themselves host the exams. There has been rampant cheating. In my country I believe the organization has resorted to manually reviewing all submissions, but I can only see this getting increasingly less effective.

This year the Canadian Computing Competition didn't officially release the final results, which for me is the best solution:

Normally, official results from the CCC would be released shortly after the contest. For this year’s contest, however, we will not be releasing official results. The reason for this is the significant number of students who violated the CCC Rules. In particular, it is clear that many students submitted code that they did not write themselves, relying instead on forbidden external help. As such, the reliability of “ranking” students would neither be equitable, fair, or accurate.

Available here: [PDF] https://cemc.uwaterloo.ca/sites/default/files/documents/2025...

Online competitions are just hopeless. AtCoder and Codeforces have rules against AI but no way to enforce them. A minimally competent cheater is impossible to detect. Meta Hacker Cup has a long history and is backed by a large company, but had its leaderboard crowded by cheaters this year.

gregdeon• 8 months ago

Oof. I had a great time cracking the top 100 of Advent of Code back in 2020. Bittersweet to know that I got in while it was still a fun challenge for humans.

singron• 8 months 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

jjice• 8 months 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!

PapstJL4U2• 8 months ago

Yeah, last year I only got to Day7 (on dec 26). I hope the smaller amount reduces "the fear of falling behind".

DangitBobby2• 8 months ago

I agree so much. Maybe I'll finally get a year done!

schaefer• 8 months ago

I’m so excited for this year.

alxndr• 8 months ago

IMHO they’re starting off harder this year!

lencastre3• 8 months ago

o’rly? I had no idea, why do you say that?

udev40963• 8 months ago

Would love to know which exotic and niche languages are people going to use for this year. I am personally thinking of trying out Crystal or Elixir

christophilus2• 8 months ago

I’m probably going to use rescript. Though I may do Gleam or Roc.

rtfeldman• 8 months ago

If you're feeling adventurous and would like to try Roc's new compiler, I put together a quick tutorial for it!

https://gist.github.com/rtfeldman/f46bcbfe5132d62c4095dfa687...

queuebert3• 8 months ago

BQN or its ancestor APL are good for this.

jeroenhd3• 8 months 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?

codr72• 8 months ago

I've been looking forward to this!

It's kotlin and shik for me this year, probably a bit of both. And no stupid competitions, AoC should be fun.

https://gitlab.com/codr7/shik

d--b2• 8 months ago

Personally, I never understood the grind of the advent of code. This is exactly the kind of stuff I am grateful to be able to delegate to a LLM.

Snacklive• 8 months ago

why would delegate to an LLM something that is supposed to be fun. THIS specifically is the kind of stuff you shouldn't delegate to an LLM

yeasku2• 8 months ago

Because they are not a hacker, but post on hackernews every day.

d--b2• 8 months ago

Well, my point, if it wasn’t clear, was that I simply don’t find those problems fun.

I enjoy programming a lot, but most of it comes from things like designing APIs that work well and that people enjoy using, or finding things that allow me to delete on ton of legacy code.

I did try to do the advent of code many times. Usually I get bored half way through reading the first problem. and then when I finally get through I realize that these usually involve tradeoffs that are annoying to make in terms of memory/cpu usage and also several edge cases to deal with.

it really feels more like work than play.

poulpy1233• 8 months ago

Going blind with uiua this year.

smokel2• 8 months ago

For those who think this is a typo, uiua [1] (pronounced "wee-wuh") is a stack-based array programming language.

I solved a few problems with it last year, and it is amazing how compact the solutions are. It also messes with your head, and the community surrounding it is interesting. Highly recommended.

[1] https://www.uiua.org/

dang• 8 months ago

Uiua – A stack-based array programming language - https://news.ycombinator.com/item?id=42590483 - Jan 2025 (6 comments)

Uiua: A minimal stack-based, array-based language - https://news.ycombinator.com/item?id=37673127 - Sept 2023 (104 comments)

poulpy1233• 8 months ago

<narrator voice>That was a bold choice that it didn't go well</narrator voice>

alexfoo11• 8 months ago

Looking forward to it but also sad that it is "only" 12 puzzles, but I completely respect Eric's decision to scale it back.

I've got 500 stars (i.e. I've completed every day of all 10 previous years) but not always on the day the puzzles were available, probably 430/500 on the day. (I should say I find the vast majority of AoC relatively easy as I've got a strong grounding in both Maths and Comp Sci.)

First of all I only found out about AoC in 2017 and so I did 2015 and 2016 retrospectively.

Secondly I can keep up with the time commitments required up until about the 22nd-24th (which is when I usually stop working for Christmas). From then time with my wife/kids takes precedence. I'll usually wrap up the last bits sometime from the 27th onwards.

I've never concerned myself with the pointy end of the leaderboards due to timezones as the new puzzles appear at 5am local time for me and I've no desire to be awake at that time if I can avoid it, certainly not for 25 days straight. I expect that's true of a large percentage of people participating in AoC too.

My simple aim every day is that my rank for solving part 2 of a day is considerably lower than my rank for solving part 1.

(To be clear, even if I was up and firing at 5am my time every day I doubt I could consistently get a top 100 rank. I've got ten or so 300-1000 ranks by starting ~2 hours later but that's about it. Props to the people who can consistently appear in the top 100. I also start most days from scratch whilst many people competing for the top 100 have lots of pre-written code to parse things or perform the common algorithms.)

I also use the puzzles to keep me on my toes in terms of programming and I've completed every day in one of Perl, C or Go and I've gone back and produced solutions in all 3 of those for most days. Plus some random days can be done easily on the command-line piping things through awk, sed, sort, grep, and the like.

The point of AoC is that everyone is free to take whatever they want from it.

Some use it to learn a new programming language. Some use it to learn their first language and only get a few days into it. Some use it to make videos to help others on how to program in a specific language. Some use it to learn how/when to use structures like arrays, hashes/maps, red-black trees, etc, and then how/when to use classic Comp Sci algorithms like A* or SAT solvers, Djikstra's, etc all the way to some random esoteric things like Andrew's monotone chain convex hull algorithm for calculating the perimeter of a convex hull. There are also the mathsy type problems often involving Chinese Remainder Theorem and/or some variation of finite fields.

My main goal is to come up with code that is easy to follow and performs well as a general solution rather than overly specific to my individual input. I've also solved most years with a sub 1 second total runtime (per year, so each day averages less than 40msec runtime).

Anyway, roll on tomorrow. I'll get to the day 1 problem once I've got my kid up and out the door to go to school as that's my immediate priority.

deergomoo2• 8 months 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.

alexfoo11• 8 months ago

Got to agree. I'm even surprised at just how little progress many of my friends and ex-colleagues over the years make given that they hold down reasonable developer jobs.

sethops1• 8 months ago

I think this has a lot more to do with time commitment. Once the problems take more than ~1 hour I tend to stop because I have stuff to do, like a job that already involves coding.

crystal_revenge4• 8 months ago

My experience has been "little progress" is related to the fact that, while AoC is insanely fun, it always occurs during a time of year when I have the least free time.

Maybe when I was in college (if AoC had existed back then) I could have kept pace, but if part of your life is also running a household, then between wrapping up projects for work, finalizing various commitments I want wrapped up for the year, getting together with family and friends for various celebrations, and finally travel and/or preparing your own house for guests, I'm lucky if I have time to sit down with a cocktail and book the week before Christmas.

Seeing the format changed to 12 days makes me think this might be the first time in years I could seriously consider doing it (to completion).

ryandv5• 8 months ago

Why try any more? There are so many fucking frauds in this field.

ksenzee• 8 months ago

This type of problem has very little resemblance to the problems I solve professionally - I’m usually one level of abstraction up. If I run into something that requires anything even as complicated as a DAG it’s a good day.

onion2k2• 8 months ago

In order to complete AoC you need more than just the ability to write code and solve problems. You need to find abstract problem-solving motivating. A lot of people don't see the point in competing for social capital (internet points) or expending time and energy on problems that won't live on after they've completed them.

I have no evidence to say this, but I'd guess a lot more people give up on AoC because they don't want to put in the time needed than give up because they're not capable of progressing.

TiredOfLife• 8 months ago

Because like 80% of AoC problems require deep Computer science background and deeply specific algorithms almost nobody is using in their day to day work.

macintux• 8 months ago

Someone else in the thread lamented the problems as "too easy" and I wondered what world I was living in.

booleandilemma• 8 months ago

It's just bluffing, lying. People lie to make others think they're hot shit. It's like the guy in school who gets straight A's and says he never studies. Yeah I'll bet.

alexfoo11• 8 months ago

The group of people for which the problems are "too easy" is probably quite small.

According to Eric last year (https://www.reddit.com/r/adventofcode/comments/1hly9dw/2024_...) there were 559 people that had obtained all 500 stars. I'm happy to be one of them.

The actual number is going to be higher as more people will have finished the puzzles since then, and many people may have finished all of the puzzles but split across more than one account.

Then again, I'm sure there's a reasonable number of people who have only completed certain puzzles because they found someone else's code on the AoC subreddit and ran that against their input, or got a huge hint from there without which they'd never solve it on their own. (To be clear, I don't mind the latter as it's just a trigger for someone to learn something they didn't know before, but just running someone else's code is not helping them if they don't dig into it further and understand how/why it works.)

There's definitely a certain specific set of knowledge areas that really helps solve AoC puzzles. It's a combination of classic Comp Sci theory (A*/SAT solvers, Dijkstra's algorithm, breadth/depth first searches, parsing, regex, string processing, data structures, dynamic programming, memoization, etc) and Mathematics (finite fields and modular arithmetic, Chinese Remainder Theorem, geometry, combinatorics, grids and coordinates, graph theory, etc).

Not many people have all those skills to the required level to find the majority of AoC "easy". There's no obvious common path to accruing this particular knowledge set. A traditional Comp Sci background may not provide all of the Mathematics required. A Mathematics background may leave you short on the Comp Sci theory front.

My own experience is unusual. I've got two separate bachelors degrees; one in Comp Sci and one in Mathematics with a 7 year gap between them, those degrees and 25+ years of doing software development as a job means I do find the vast majority of AoC quite easy, but not all of it, there are still some stinkers.

Being able to look at an AoC problem and think "There's some algorithm behind this, what is it?" is hugely helpful.

The "Slam Shuffle" problem (2019 day 22) was a classic example of this that sticks in my mind. The magnitude of the numbers involved in part 2 of that problem made it clear that a naive iteration approach was out of the question, so there had to be a more direct path to the answer.

As I write the code for part 1 of any problem I tend to think "What is the twist for part 2 going to be? How is Eric going to make it orders of magnitude harder?" Sometimes I even guess right, sometimes it's just plain evil.

mattbillenstein3• 8 months ago

Realize in anything, there are people who are much better than even the very best. The people doing official collegiate level competitive programming would find AoC problems pretty easy.

rts_cts• 8 months ago

I have a EE background not CS and haven't had too much trouble the last few years. I'm not aiming to be on the global leader board though. I think that with good problem solving skill, you should be able to push through the first 10 days most years. Some years were more front loaded though.

duxup• 8 months ago

On sorta the same topic:

In the programming world I feel like there's a lot of info "for beginners" and a lot of folks / activities for experts.

But that middle ground world is strange... a lot of it is a combo of filling in "basics" and also touching more advanced topics at the same time and the amount of content and just activities filling that in seems very low. I get it though, the middle ground skilled audience is a great mix of what they do or do not know / can or can not solve.

I don't know if that made any sense.

josephg• 8 months ago

This is also true of a lot of other disciplines. I’ve been learning filmmaking lately (and editing, colour science, etc). There’s functionally infinite beginner friendly videos online on anything you can imagine. But very little content that slowly teaches the fundamentals, or presents intermediate skills. It’s all “Here’s 5 pieces of gear you need!” “One trick that will make your lighting better”. But that’s mostly it. There’s almost no intermediate stuff. No 3 hour videos explaining in detail how to set up an interview properly. Stuff like that.

greener_grass• 8 months ago

CodeWars has a nice Kata grading system that features many intermediate level problems.

ahoka4• 8 months ago

Yes, and it's hard to point to reference material to newcomers. Hey, yeah that's actually a classic problem, let me show you some book about this... oh there's none. Maybe I should start creating them, but that is of course hard.

But also, the middle ground is often just years of practice.

Vinnl• 8 months ago

Makes sense that that's the case: there's usually a limited amount of beginner's knowledge, and then you get to the medium level by arbitrary combinations of that beginner's knowledge, of which there's an exponential number, making it less likely that someone has produced something about that specific combination. Then at the expert level, people can get real deep into some obscure nitty-gritty detail, and other experts will be able to generalise from that by themselves.

fifilura• 8 months ago

Middle level is where you pay with sweat.

joseda-hg• 8 months ago

It's one of the worst parts of being self taught, beginner level stuff has a large interest base because everyone can get into it.

Advanced level stuff usually gets recommended directly by experts or will be interesting to beginners too as a way of seeing the high level.

Mid level stuff doesn't have that wide appeal, the freshness in the mind of the experts, or the ease of getting into, so it's not usually worth it for creators if the main metric is reach/interest

Structured (taught) learning is better in this regard, it at least gives you structure to cling on to at the mid level

llmthrow0827• 8 months ago

It's totally true. I was doing Advent of Code before I had any training or work in programming at all, and a lot of it can be done with just thinking through the problem logically and using basic problem solving. If you can reason a word problem into what it's asking, then break it down into steps, you're 90% of the way there.

ab5tract• 8 months ago

The statistics speak a far different story, I’m afraid.

gardenhedge• 8 months ago

Agreed. I have a CS background and years of experience but I don't get very far with these. At some point it becomes a very large time commitment as well which I don't have

magimas• 8 months ago

mh, maybe it's cheating because it's still a STEM degree but I have a PhD in physics without any real computer science courses (obviously had computational physics courses etc. though) and I managed to 100% solve quite a few years without too much trouble. (though far away from the global leaderboard and with the last few days always taking several hours to solve)

eloisant• 8 months ago

The point is not that it's easy, but that you don't need much knowledge beyond knowing how to code.

In this sense it's accessible: you won't get stuck because of a word you don't understand or a concept you've never heard of.

deergomoo2• 8 months ago

you won't get stuck because of a word you don't understand or a concept you've never heard of

I very much disagree here. To make any sort of progress in AoC, in my experience, you need at least:

- awareness of graphs and how to traverse them

- some knowledge of a pathfinding algorithm

- an understanding of memoisation and how it can be applied to make deeply recursive computations feasible

Those types of puzzle come up a lot, and it’s not anything close to what I’d expect someone with “just a little programming knowledge” to have.

Someone with just a little programming knowledge is probably good with branches and loops, some rudimentary OOP, and maybe knows when to use a list vs a map. They’re not gonna know much about other data structures or algorithms.

They could learn them on the go of course, but then that’s why I don’t think basic coding knowledge is enough.

Planktonne• 8 months ago

In general, the problems require less background knowledge than other coding puzzles. They're not always accessible without knowing a particular algorithm, but they're more 'can you think through a problem' than 'have you done this module'.

That's not the same as saying they're easy, but it's a different kind of barrier, and (in my opinion) more a test of 'can you think?' than 'did you do a CS degree?'

saberience6• 8 months ago

Agreed. There is no "beginner" or amateur programmer who could complete even part of a single Advent of Code problem.

alexfoo11• 8 months ago

I disagree, the odd few are quite simple and can be done with pencil and paper.

https://adventofcode.com/2020/day/1 for example. It's not hard to do part 1 by hand.

You need two numbers from the input list (of 200 numbers) that add to 2020.

For each number n in the list you just have to check if (2020-n) is in the list.

A quick visual scan showed my input only had 9 numbers that were less than 1010, so I'd only have to consider 9 candidate numbers.

It would also be trivial for anyone who can do relatively simple things with a spreadsheet.

alach11• 8 months ago

Usually the first day or two are readily solvable in Excel with just regular spreadsheet formulas.

bigell• 8 months 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.

alexfoo11• 8 months ago

Some part of me would love a job that was effectively solving AoC type problems all the time, but then I'd probably burn out pretty quickly if that's all I ever had to do.

Sometimes it's nice to have a break by writing a load of error handling, system architecture documentation, test cases, etc.

For me it's a great chance to sharpen the tools in my toolbox.

That's a good way of putting it.

My way of taking it a step further and honing my AoC solutions is to make them more efficient whilst ensuring they are still easy to follow, and to make sure they work on as many different inputs as possible (to ensure I'm not solving a specific instance based on my personal input). I keep improving and chipping away at the previous years problems in the 11 months between Decembers.

sizzzzlerz• 8 months 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.

sureglymop• 8 months ago

I want to try doing it in assembly using fasm this year.

Could either be really recreational and relaxing.. or painful and annoying.

Though I don't care even if it takes me all of next year, it's all in order to learn :)

bob-surfs• 8 months ago

Where my Gleamlins at? Who else is using Gleam this year?

tylerchurch• 8 months ago

I am! I love the design of Gleam in theory but keep bouncing off it so I’m interested in seeing if AoC will help me give it a fair shake.

enby_instrument• 8 months ago

I can't wait to try this year's challenges.

fud101• 8 months ago

I've never done this before but honestly I am just turned off by the website and font being hard to read. I get that's the geek aesthetic or whatever, but it's a huge turn off for me.

zootboy• 8 months ago

There's a relevant FAQ with a solution for you:

https://adventofcode.com/2025/about#faq_highcontrast

perlperson• 8 months 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.

vidyesh• 8 months ago

Other Advent Calendars for developers https://github.com/vimode/Advent-Calendars-For-Developers

I am still updating it for this year, so please feel free to submit a PR or share some here.

aadv1k• 8 months 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!

mattbillenstein3• 8 months 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.

adastra22• 8 months ago

Hate to be that guy, but this is unreadably small text on mobile.

mnafees• 8 months ago

I love Advent of Code! I have used previous years' problems for my guest lectures to Computer Science students and they have all enjoyed those more than a traditional algorithmic lecture.

itzjacki• 8 months ago

Finally that time of year again! I've been looking forward to this for a long time. I usually drop off about halfway anyways (finished day 13, 14 and 13 the previous 3 years), as that's when December gets too busy for me to enjoy it properly, so I personally don't mind the reduction in problems at all, really. I'm just happy we still have great puzzles to look forward to.

spooky_deep• 8 months ago

Do the problems get harder each day?

The-Ludwig• 8 months ago

Yes! With difficulty usually peaking on the weekends.

wodenokoto• 8 months ago

Oh… I’ve never done these “in time” and wondered why the next day problem felt so much easier.

I always put it down to overthinking and never arriving at a solution but maybe it was actually a much tougher problem!

roman_soldier3• 8 months ago

Not a fan of these "Coding for fun" things. Code for a job to earn money, yes, a side project where there is an end goal, yes. This seems like a waste of time for working developer.

Maybe it's useful for people trying to learn but also becoming pointless now as all Junior dev roles can be done with AI.

I mean do plumbers have an advent of plumbing where they try and unblock shit filled toilets for fun?

stablesteady• 8 months ago

It's literally just puzzles which have to be solved through code. Solving puzzles is a very normal thing to do for many people

roman_soldier3• 8 months ago

Never got that, I have plenty of "puzzles" to solve in work and life which have real outcomes. I guess Im too utilitarian to enjoy puzzles with ROI.

torben-friis• 8 months ago

I mean do plumbers have an advent of plumbing where they try and unblock shit filled toilets for fun?

No, but you’ll see it for writers, musicians, and the like.

Engineering (software or not) can be an intellectually rewarding experience for many. I don’t know why some people find this something to scoff at, would you rather have no pleasure derived from your work?

roman_soldier3• 8 months ago

No I get that, it's just not for me that's all.

davey48016• 8 months ago

I can't find it, but this question got asked somewhere (Reddit maybe) about 8-10 years ago, and a plumber took the time to respond that many plumbers are actually very passionate about what they do. They don't specifically unclog toilets for fun, but there are plumbers that spend a lot of their free time on plumbing forums, and even some who have projects experimenting with different ways to install certain things.

gus_massa• 8 months ago

I just found in Google (don't worry, SFW)

https://www.plumbingnationals.com/

https://www.youtube.com/watch?v=BWrvnNMsmeM

dgb23• 8 months ago

I mean do plumbers have an advent of plumbing where they try and unblock shit filled toilets for fun?

Yes, plumbers and other types of craftspeople and technicians do also have these little fun competitions. Why shouldn't they?

I think the reason some of us programmers do these things, is likely because many (myself included) entered the field as enthusiasts and hobbyists in the first place.

talideon3• 8 months ago

mean do plumbers have an advent of plumbing where they try and unblock shit filled toilets for fun?

You've obviously never watched "Drain Cleaning Australia" on YouTube!

Yes, some people find this stuff fun, because they find coding fun, and don't typically get to do the fun kind of coding on company time. Also, there'd be a hell of a lot less open source software in the world if people didn't code for fun.

Let people enjoy things. Just because you don't like that par of your job as much as them doesn't mean they're wrong.

ngrislain3• 8 months ago

A good opportunity to learn a new programming language: https://news.ycombinator.com/item?id=46105849

fnands• 8 months ago

Doing it in Mojo this year.

Much easier so far than it was in 2023 when just basic string wrangling was basically nonexistent.

baud147258• 8 months ago

well, I tried to do the first day and I think it's an indictment of my own capabilities that I spent most of my day on the second part and still failed to get the correct result. That sort of programming is not something I've been doing at my current position, but still as programmer that has been working for a decade, that smarts a little.

mclau153• 8 months ago

"That's not the right answer; your answer is too low. Curiously, it's the right answer for someone else; you might be logged in to the wrong account or just unlucky. In any case, you need to be using your puzzle input. If you're stuck, make sure you're using the full input data; there are also some general tips on the about page, or you can ask for hints on the subreddit. Please wait one minute before trying again. [Return to Day 1]"

Alive-in-20253• 8 months ago

I'm getting this too, what did you do about? It seems to be switching me between two datasets. I downloaded the data again. When I click on "go back to problem 1", that's when it happens.

1vuio0pswjnm7• 8 months ago

Is it necesary to "log in" with a so-called "tech" company such as Github (Microsoft), Reddit, Google, etc., in order to see the puzzles

Jtsummers5• 8 months ago

Only to see half the puzzles. You can see the rest without logging in.

henhouseai• 8 months 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.

stOneskull4• 8 months ago

the adventofcode subbreddit is pretty cool to visit once you've finished. i learned a new approach (for puzzle 2/2) that i wouldn't have, as my first approach was 'good enough' and i would've left it at that.

Alive-in-20253• 8 months ago

I do love this, did it last year, but the system keeps seeming to switch its notion of what dataset I'm supposed to be using. I used git auth.

I'm having a problem where the webpage switches me to a different dataset. I've been logged in the entire time in the same session, same user. I get "wrong answer but that's the answer for a different dataset". It seems to be switching me between two "problem sets". Then it keeps telling me I'm submitting answers too fast.

Originally I saved my dataset as "prob1-test.txt". It kept telling me I had the wrong answer. I did some debugging, perhaps I fixed a bug but I'm not sure.

Then I downloaded the dataset again after I really thought I had it right and tried a bunch of other things. I got a completely different data set! Call this "prob1-test-ds2.txt". I submitted an answer on data set 2 and it was accepted.

So I'm on to part 2 of the day 1 problem. I have the same problem again, I think it's right (but not impossible it could be wrong ;-)). It's giving me this feedback:

If I had to guess, as part of debugging this I get a "go back to problem 1 definition" after getting a "wrong answer" result.

Pretty sure it's working now that I have the "this is the answer for another dataset" message, but I keep getting either "this is the answer for another dataset" or "too many submissions". I'm waiting a few minutes between them.

How can I fix this switcheroo problem.

Alive-in-20253• 8 months ago

Update - I see someone reported the same thing below.

I know how you might fix it, put a dataset set ID at the start of the dataset and tell people to skip it. Like (# 9481818). and you have to put that in your answer. This way you could detect this bug.

greenido• 8 months ago

I still love solving them myself (30-90 min/day, no copy-paste), and private leaderboards with friends feel as human as ever.

Advent of Code 2025

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