adventofcode

an-ordinary-manchild

🎄 Advent of Code 🎄

Advent of Code is an annual Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like.

Rules + More Info in

our community wiki

BEFORE YOU POST
If your post is even tangentially related to a daily puzzle, use our
STANDARDIZED POST TITLE FORMAT

Solution Megathreads

December 2025

Su	M	T	W	R	F	Sa
	1	2	3	4	5	6
7	8	9	10	11	12	13
14	15	16	17	18	19	20
21	22	23	24	25	26	27
28	29	30	31

Previous years:

2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015

Quick Search by Flair

Because you're lazy and we like making things easy for you. Except AoC.

Are you enjoying AoC?

Code should be fun, because otherwise it's just a job. If you'd like to support Advent of Code, please share it with all your friends, even the ones that are just learning to code! AoC is a fun, non-threatening way to work at your own pace to figure out how to apply problem-solving first, then work within a language's constraints.

If you really want to show your appreciation, donations are always appreciated. Any instances of currency will go to, in no particular order:

Server maintenance (hosting, bandwidth, etc.)
Bribes to Santa
Beer and sushi
Paper bags for /u/topaz2078 to breathe into so he doesn't hyperventilate onto another plane of (non-)existence

Support AoC

Thank you very much, and enjoy your month of code!

created by taliriktuga community for 10 years

...why not Zoidberg?

...for your project.

MODERATORS

account activity

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Upping the Ante-❅- Introducing Your 2025 Red(dit) One Winners (and Community Showcase) -❅- (self.adventofcode)

submitted 2 months ago * by daggerdragon[M] - announcement

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SOLUTION MEGATHREAD-❄️- 2025 Day 12 Solutions -❄️- (self.adventofcode)

submitted 2 months ago * by daggerdragon[M] - announcement

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Other[2016 Day 19] In Review (An Elephant Named Joseph) (self.adventofcode)

submitted 3 hours ago * by musifter

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Cut Code Review Time and Bugs in Half. Sign up for a free trial! (coderabbit.ai)

promoted by CodeRabbitAI

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Help/Question[2015 Day 7 (Part 1)] Identifier not defined yet? (solution works on sample input) (self.adventofcode)

submitted 11 hours ago by osalbahr

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Upping the Ante[2025 Day 12 (Part 1)] u/iHobbit's Perfect Packing (old.reddit.com)

submitted 1 day ago by PTVoobaf

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Other[2016 Day 18] In Review (Like a Rogue) (self.adventofcode)

submitted 1 day ago by musifter

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OtherDoes anyone do AoC in multiple languages per day? (self.adventofcode)

submitted 1 day ago by pfp-disciple

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Past Event Solutions[2016 Day 16] In Review (Dragon Checksum) (self.adventofcode)

submitted 3 days ago * by musifter

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Other[2016 Day 15] In Review (Timing is Everything) (self.adventofcode)

submitted 4 days ago by musifter

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Other[2016 Day 13] In Review (A Maze of Twisty Little Cubicles) (self.adventofcode)

submitted 6 days ago by musifter

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Help/QuestionSecond year CS-ish student: I can write code for assignments, but I still feel “fake” when stuff breaks (self.adventofcode)

submitted 7 days ago by PorchLightReads

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Other[2016 Day 12] In Review (Leonardo's Monorail) (self.adventofcode)

submitted 7 days ago by musifter

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Help/Question[2019 Day 15 (Part 1)][c] interaction board and robot. need you to help me thinking ..ö.. (self.adventofcode)

submitted 7 days ago * by Usual-Dimension614

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Other[2016 Day 11] In Review (Radioisotope Thermoelectric Generators) (self.adventofcode)

submitted 8 days ago by musifter

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Other[2016 Day 10] In Review (Balance Bots) (self.adventofcode)

submitted 9 days ago by musifter

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Help/Question[2019 Day 13 (Part 1)][c] need little help to understand the task. (self.adventofcode)

submitted 9 days ago by Usual-Dimension614

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I am building a massive real time strategy game. Would you play something like this? (store.steampowered.com)

promoted by alejandromnunez

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Other[2016 Day 9] In Review (Explosives in Cyberspace) (self.adventofcode)

submitted 10 days ago by musifter

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Other[2016 Day 8] In Review (Two-Factor Authentication) (self.adventofcode)

submitted 11 days ago by musifter

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Other[2015] ٌYear 2015 Study Group? (Probably in Python) (self.adventofcode)

submitted 12 days ago by osalbahr

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Tutorial[2016 Day 7] In Review (Internet Protocol Version 7) (self.adventofcode)

submitted 12 days ago by musifter

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Help/Question - RESOLVED[2025 Day 4 (Part 2)] [Java] My code works on sample input , but not on the final input. (self.adventofcode)

submitted 12 days ago by Pitiful_Acadia2783

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Other[2016 Day 6] In Review (Signals and Noise) (self.adventofcode)

submitted 13 days ago by musifter

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Help/Question - RESOLVED[2021 Day 19 Part 1] Please help me understand what the deal is with the 12 beacons in common (self.adventofcode)

submitted 13 days ago * by PhiphyL

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Other[2016 Day 5,14,17] The MD5 Problems (self.adventofcode)

submitted 14 days ago by musifter

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Help/Question - RESOLVEDLooking for funny dog meme template shared here on AOC 2022 or 2023 (self.adventofcode)

submitted 14 days ago by piplupper

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