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
Only to see half the puzzles. You can see the rest without logging in.
Advent of Code 2025
391–400 of 416 posts
Re: Advent of Code 2025
#392Earlier quoted context omitted.
Yep, I don't really understand why the author didn't make it one per day for 24 days. Am I missing something obvious?
Since the start, each problem has 2 parts (2 "stars"). Part one sets up the problem, ensures you have parsed the input correctly, etc. After submitting the correct answer to that part, part 2 is revealed, which sometimes expands the proplem space, adds new limits, etc. Something that solves part 1 might be inadequate for part 2.
Yes, but nothing (theoretically) stops him from saying: "congratulations, you have solved part 1, wait until tomorrow for part 2".
I think either the author thinks people appreciate more the 2 stages challenge, than having one problem each day; or, more likely, the whole "infrastructure" is already prepared for 2 stages challenges per day. And changing that meant more work, eventually touching literally 10 y.o. code. The reason for the reduced days is exactly the lack of time. I assume he preferred to have 12 days, and modify as little as possible the old code. Having 1 stage per day maybe would have been possible at the expense of having less challenges, which again defeats the purpose.
Re: Advent of Code 2025
#393Earlier quoted context omitted.
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 y…
any recommendations on how to do this?
One way I've found is to break the problem down, and think about each step in reverse. So for example, what does the final stage want to do in order to achieve the result in a simple way? It might be that to get the final result it needs to sum numbers, but also needs to know their matching index in another array, plus some other identifier you got from an as-yet-unwritten previous step. This means your final stage needs a bunch of records that are (number, idx, sourceId), which means the step before needs to construct them - what information does it need to transform into that?
Write the simple code you want to write, and think about what makes the prior step possible in the easiest way and build your structures from there, filling in the gaps.
Re: Advent of Code 2025
#394Earlier quoted context omitted.
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.
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.
Agreed! It’d be nice to surface that somehow. The subreddit is good but not everyone is there. I found a lot of interesting people and code in the folks who managed to finish challenges in like 4 minutes or whatever..
Re: Advent of Code 2025
#395Earlier quoted context omitted.
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.
Isn't the whole point of AoC to NOT use AI? Even says so in the FAQ
Yes, I'm doing it without AI to learn the language, nonetheless I do think that Lean 4 + AI is a super-powerful combination.
Re: Advent of Code 2025
#396Earlier quoted context omitted.
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.
Given what I understand about the nature of competitive programming competitions, using an LLM seems kind of like using a calculator in an arithmetic competition (if such a thing existed) or a dictionary in a spelling bee.
I feel like it’s more like using an electronic dictionary in a spelling bee that already allowed you to use a paper dictionary. All it really does is demonstrate that the format isn’t suited to be a competition in the first place.
Which is why I think it’s great they dropped the competitive part and have just made it an advent calendar. Much better that way.
Re: Advent of Code 2025
#397I 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.
Re: Advent of Code 2025
#398I 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 th…
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.
Re: Advent of Code 2025
#399Opinion 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).
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, ...
Re: Advent of Code 2025
#400Earlier quoted context omitted.
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.
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.
There are several sets of inputs, and it picks one for you.