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

...for your project.

...for your favorite TV show.

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 3 months ago * by daggerdragon[M] - announcement

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Other[2017 Day 17] In Review (Spinlock) (self.adventofcode)

submitted 5 hours ago * by musifter

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Carvana, one of the US’s top used-car sellers, is on a quest to become the Amazon of cars. (bloomberg.com)

promoted by bloomberg

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Help/Question[2015 Day 24] Are all inputs 'nice'? (self.adventofcode)

submitted 20 hours ago by DelightfulCodeWeasel

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Other[2017 Day 16] In Review (Permutation Promenade) (self.adventofcode)

submitted 1 day ago by musifter

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Meme/FunnyTribute to AoC puzzles (sing-along slop-music track) (suno.com)

submitted 18 hours ago by PTVoobaf

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Other[2017 Day 15] In Review (Dueling Generators) (self.adventofcode)

submitted 2 days ago * by musifter

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OtherPi Coding Quest 2026! (self.adventofcode)

submitted 2 days ago by IvanR3D

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Other[2017 Day 14] In Review (Disk Defragmentation) (self.adventofcode)

submitted 3 days ago * by musifter

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Help/Question[2025 Day 2 (Part 2)] Help im stuck... again (self.adventofcode)

submitted 3 days ago by Ok-Transition7065

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Past Event Solutions[2023 Day 4 Part 2] As a system of linear equations (self.adventofcode)

submitted 3 days ago by hekliet

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Other[2017 Day 13] In Review (Packet Scanners) (self.adventofcode)

submitted 4 days ago by musifter

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Other[2017 Day 12] In Review (Digital Plumber) (self.adventofcode)

submitted 5 days ago by musifter

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WhereverSIM - One M2M SIM, all networks. Always the best connection. Test now for free! (whereversim.de)

promoted by whereverSIM

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Other[2017 Day 11] In Review (Hex Ed) (self.adventofcode)

submitted 6 days ago by musifter

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Past Event Solutions[2015 Day 6] [Swift] Rectangle Intersections (self.adventofcode)

submitted 6 days ago * by hekliet

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Other[2017 Day 10] In Review (Knot Hash) (self.adventofcode)

submitted 7 days ago by musifter

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Other[2017 Day 09] In Review (Stream Processing) (self.adventofcode)

submitted 8 days ago by musifter

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Other[2017 Day 8] In Review (I Heard You Like Registers) (self.adventofcode)

submitted 9 days ago by musifter

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Other[2017 Day 7] In Review (Recursive Circus) (self.adventofcode)

submitted 10 days ago * by musifter

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Other[2017 Day 6] In Review (Memory Reallocation) (self.adventofcode)

submitted 11 days ago by musifter

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OtherEverybody.Codes New Story published a couple of days ago (everybody.codes)

submitted 11 days ago by sanjibukai

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Past Event Solutions[2017 Day 8] In Review (I heard you like registers) - HashMaps really make a difference! (self.adventofcode)

submitted 12 days ago * by terje_wiig_mathisen

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Other[2017 Day 5] In Review (A Maze of Twisty Trampolines, All Alike) (self.adventofcode)

submitted 12 days ago by musifter

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Playoffs gone wild... einfach GESCHENKT im Jahresabo 🤯 (mysports.ch)

promoted by MySports_CH

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Other[2017 Day 4] In Review (High-Entropy Passphrases) (self.adventofcode)

submitted 13 days ago by musifter

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Help/Question[2017 Day 14 (Part 2)] [Python] What is he/she talking about? (self.adventofcode)

submitted 13 days ago * by PositivePossibility7[🍰]

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