Advent of Code 2025: Number of puzzles reduce from 25 to 12 for the first time
48 comments
·October 26, 2025thomascountz
TeMPOraL
Hate to be the... whoever I'm being right now, but names have meaning. It's the reason to have them in the first place.
> Advent of Code isn't about there being 25 puzzles, and so maintaining volume at all costs has nothing to do with it.
It's the Advent of Code. Not "Random late year event with no religious / commercial tradition connotations whatsoever" of Code. The 25 is there in the name. It's the whole point :).
flumpcakes
Advent does not mean 25. You could have checked a dictionary. You might be confused because as a child you ate 25 chocolates leading up to Christmas day but you shouldn't use that as a reason to criticise something.
petesergeant
I’ve been trying to design a puzzle for a game this year that humans can solve but LLMs can’t. I’ve come up with one, but it was hard work! It’s based around message cracking.
ekimekim
There was one in a previous AoC that I think stumped a lot of AI at the time because it involved something that was similar to poker with the same terminology but different rules. The AI couldn't help but fall into a "this is poker" trap and make a solution that follows the standard rules.
sunrunner
Was that 2023's Day 7 'Camel Cards' [1]?
gf000
I mean, wasn't pretty much the second half of all AoC exercises beyond LLM capabilities?
I remember there being multiple accounts trying to one-shot AoC and all ended on day 10 or so.
petesergeant
Interesting! Maybe that’s the general way to approach these things
Gigachad
Have a look at https://arcprize.org/
They have hundreds of challenges that humans can solve in under a minute which LLMs can not. Seems the general trend is figuring out the rules or patterns of the challenge when there are few examples and no instructions.
petesergeant
Ah, it also needs to be challenging for humans. It's a prize to win something. I just didn't want people to throw the question into Claude Code.
huflungdung
[dead]
thaumasiotes
> And with that, I had to remind myself: Advent of Code isn't about there being 25 puzzles
Really? The name of the event is "Advent of Code". Having 25 puzzles is easily its most strongly-determined aspect.
You could argue for 23-29 puzzles, or perhaps for 5, but at 12 what's the name supposed to refer to?
matrss
IMO "Advent of Code" only determines the timeframe in which it happens, not the amount of puzzles it must contain. It could just as well be four puzzles, one for each sunday of the advent, or any other amount, as long as they are released within those roughly four weeks before christmas.
danielbln
Eh, the implication has always been that it's a Christmas calendar where you open one door per day until it's Christmas eve - just with code riddles instead of chocolate.
akho
Twelve nights of Christmas. Would also work better for me, calendar-wise :)
ThunderSizzle
That would "require" a timeline shift for it to start on Christmas run until the Ephinany.
Although I don't think anyone really knows what the 12 days of Christmas are anymore.
eterm
Well advent calendars traditionally had 24 doors.
shrx
One of the reasons I stopped participating was that as the second half of december was approaching I had less and less free time for solving the puzzles. So to me it is also a welcome change, I will try to finish it again this year.
rich_sasha
I once has this half serious idea to do "Advent of Parenting", with one problem per month, and you start after Christmas. As in, youre so delayed you start in the New Year, and have time for one problem per month.
But hey I didn't have the time to do it. Kids...
NoboruWataya
Same, I love AoC but I just never have time for them (December is always the busiest time of year in my job).
I would have liked if a puzzle was released every 2 days though so it still spanned the whole month. Would be more aligned with the advent calendar concept. In fact in previous years the puzzles have always had two parts so if that format is still being retained there will still effectively be 24 puzzles.
emerongi
Spreading the two parts across separate days would be interesting. There would be an extra element of trying to predict what part 2 will be like.
seabombs
Agree. It was getting in the way of me spending time with the family because I was distracted mulling over the puzzles.
I had thought last year that they could peak the difficulty around the middle of the month and bring it down a bit leading up to the 25th. But just finishing it earlier is probably better IMO.
jojobas
Doesn't help that the puzzles become increasingly tricky and you can't just solve them as you sip your coffee anymore (although some apparently can).
HiPhish
If he has cut the number of puzzles in half, why not then release a new puzzle every other day? That would make more sense because AoC would still run until Christmas, and it would give people more time per puzzle. Maybe unlock part 2 of each puzzle the day after the puzzle has been posted, so there still something new every day.
I once tried participating, but gave up halfway through because one puzzle per day was just too much time. If it was one puzzle every two days it would be more manageable.
akerl_
If they’re released every day for 12 days, you can do a puzzle every other day.
If the were released every other day, people who wanted to do them for 12 straight days could not.
rootlocus
> If the were released every other day, people who wanted to do them for 12 straight days could not.
If they instead waited 12 days, they could start with the 6 puzzles already released, and then have enough puzzles to solve once a day for the next 12 days.
lexicality
I see the leaderboard is gone too. Unfortunate but entirely predictable given how the last 2 years went.
That being said, I was worried he'd cancel the entire thing, so this is still good news!
vismit2000
From FAQ: "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)."
klustregrif
Really appreciate thise changes! Both the reduction in puzzles which means less work, but overall I don’t think it’s going to make the event less fun.
And removing the global leaderboard is good, rather than trying to police how people solve the puzzles just let people have fun on their own boards with people they know.
gooodvibes
No more leaderboard too!
These look like positive changes, a 2x longer event isn't 2x more fun or 2x more satisfying to participate in.
defanor
On the bright side, this will lead to a more relaxed December schedule. I do not compete for the leaderboard, but trying to solve the puzzles on the days they are released (to keep it in the spirit of an advent calendar), and the puzzles towards the end sometimes take me a considerable chunk of the day to solve, which is tricky to combine with the regular schedule, and may be rather stressful (though still a nicer kind of "stressful", as you get on celebrated holidays).
sunrunner
This matches my experience, and I've been 'nervously' anticipating this year's Advent of Code. I managed to keep to the spirit last year and get everything done by Christmas day (though admittedly with some days bleeding over into other days due to pesky family/other commitments), but even this relied on having the last week or so of the month be relatively free for me.
While I've usually been able to do the first half of the month's puzzles in the day before breakfast, over lunch and in the evening, the increasing difficulty does mean that later puzzles can really eat into a day, particularly if you happen to go down a bad path for your solution.
cod1r
This is sort of a bummer but as long as Eric feels less stressed and more happy, I'm all for it.
aronhegedus
I've participated in the past, and felt like I always drop off around day 18+ because of holidays etc.
I personally also didn't like when part II of a question felt like a completely new question, instead of a neat extension of the previous one.
I am very happy that this is something that's available to do, for free though. I see advent of code as a good excuse to dabble with a new language, usually with a few people from work.
nikanj
Tryhards ruin everything, part n
Make a fun little christmas calendar to bring joy to the people, get turned into a gamified warzone where people use AI and bots to try to get onto the global leaderboards - possibly because getting on them might net you a job at FAANG
Udo
I know this is an outsider position, but I always felt that the AoC leaderboard was a mistake. Very few people had the time, the commitment, and the capability of making it on there in a meaningful fashion, and it put an emphasis on something that didn't match the vibe of the event at all. If speedrunning the problem solving was the point, then why package every episode into an enjoyable little story?
This also ties into the comments that AoC has become moot or was "ruined by LLMs". If you enjoy solving the problems, nothing should have changed for you. What's the difference if a given problem was already solved by an LLM, or a group of IQ 200 superhumans from MIT for that matter?
As time marches on, there will eventually be absolutely nothing left where an unaugmented human outperforms a machine. That doesn't mean you have to stop enjoying things. In a few years at most, all programming will be purely recreational.
iamflimflam1
People - the reason why we can’t have good things.
ozim
Fun part is that world mostly doesn’t really work like that and they don’t really get the job.
fjfaase
The temptation to start a competative private leader board will be great, just for the mentioned reason. I have a reference my scores in my CV. The competative part of AoC is one of the things that I find attractive and also has taught me some valuable lessons about coding, like taking some time to review the code the first time before submitting. I experienced several times that I spend of time to debug a small bug due to a minor error, that I could have caught had I spend some time reviewing. Especially with the first puzzles, I try to get it right the fitst time with respect to compiling and execution.
I will search for a pure C private group to join that only allows a small library for things like reading the input as an array of strings.
0x264
On your CV ? Has any recruiter or hiring manager ever commented on it, or said the mention gave you an advantage ?
ifh-hn
[dead]
Whenever there's a change like this, my gut reaction is to grieve and try to imagine ways that things could be kept the same.
After thinking, "maybe puzzles could be designed by a group instead of an individual and they could share the work," I then thought, "and couldn't an LLM help?"
And with that, I had to remind myself: Advent of Code isn't about there being 25 puzzles, and so maintaining volume at all costs has nothing to do with it.
And aren't we so lucky that it isn't! Aren't we lucky to have had the prior 500+ challenges given as gifts over the years! Aren't we lucky to have a great demonstration of humility and care! Aren't we lucky to have 12 new gifts to look forward to this year!
Thank you!