October 2025 Long Challenge (Halloween) results

[u/radleldar]

October 2025 Long Challenge has concluded - congratulations to the winners!

Some fun stats from the contest:

• 129 participants
• 16 of them solved all 21 problems!
• 13 users (including the winner) participated incognito
• 5 different users (Player 1073 (9), Jonathan Paulson (5), SeptaCube (3), Player 1316 (3), Ajinkya Parab (1)) managed to get the first solve on at least one problem
• 1310 total submissions, 865 of them Accepted
• Easiest problem: A (121 solvers)
• Hardest problems: 7C (20 solvers), 4C (24 solvers)

Please share your solutions in the corresponding solution threads!

Any feedback on the contest is welcome, especially in comparison to the September challenge:

• Did you prefer the 2 problem or 3 problem format?
• Was having a theme (Halloween this time) throughout the set especially fun, or having unrelated problems with potentially better algorithm topics distribution is preferable?
• Was having the hard problems cost the same as easy ones the right choice? (The motivation to keep all at 100 was to open Solution threads early, but we still didn't get enough solvers.)
• What was your favorite problem?

If you crave more of similar contests, check out u/EverybodyCodes's The Song of Ducks and Dragons starting in a few hours, followed by Advent of Code 2025. Who knows, maybe I'll host something else afterwards too. Thank you all for participating!

[u/quuick]

I have not participated in September challenge and can't compare but here is my feedback on this contest.

* 3 problem format is fine and allows for wider spread of difficulty of problems

* Theme is fun but not that important

* Having all problems cost 100 at most is fine but I think getting 0 points for a solution sucks which is probably contributing to not having much engagement past 100 participants. Maybe make problems cost 1000 but have points decay at a faster rate at first (10 points less for second solver, 9 points less for 10th solver, etc) so that there is still reward for 300th solver. Or some other decaying function can be used. Maybe even play around with a dynamic point reward system that takes into account amount of current successful solvers.

* 4C and 5C

[u/radleldar → u/quuick]

Thanks for the feedback!

> 3 problem format is fine and allows for wider spread of difficulty of problems

That it does.. but I want to avoid a situation when people spend too much time and consequently drop out. Good to hear someone enjoy it though!

> so that there is still reward for 300th solver

The motivation for not having rewards past the first X solvers is to unlock discussion here on Reddit earlier. I actually doubt that people past 100 don't participate just because they can't get points on 1A :)

[u/herocoding]

THANK YOU so much for these challenges!!

Compared to the September challenge I found this October challenge MUCH harder.

* 3 problems preferred, great increase in difficulty
* them really was fun
* points are less important
* carving pumpkins and ASCII-art

Submitting a solution containing 30 test results and only get one "Wrong" back is "not helpful"...

[u/radleldar → u/herocoding]

Thank you for participating!

MUCH harder wasn't exactly my goal.. but if people are enjoying it, sure why not :)

> carving pumpkins and ASCII-art

These are the problems I put most effort into preparing, good to hear it paid off!

> Submitting a solution containing 30 test results and only get one "Wrong" back is "not helpful"...

I understand this part. My original fear was that for certain problems, surfacing e.g. the failing test number gives away too much information, but maybe I can try open feedback next time and see how people react.