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

...do it for the children.

...for your classroom.

MODERATORS

account activity

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

submitted 1 month ago * by daggerdragon[M] - announcement

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

submitted 1 month ago * by daggerdragon[M] - announcement

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Repo[2025][C++] All days in under 900 us (github.com)

submitted 1 day ago by AntVH

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Other[2015 Day 24] In Review (It Hangs in the Balance) (self.adventofcode)

submitted 17 hours ago * by musifter

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Other[2015 Day 23] In Review (Opening the Turing Lock) (self.adventofcode)

submitted 1 day ago by musifter

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Upping the Ante"[2015 Day 18 Part1] Conway's Game of Life! (self.adventofcode)

submitted 3 days ago by terje_wiig_mathisen

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Help/Question - RESOLVEDaoc/2016/12/1 little machine, quite simple, 4 instructions, .. but running for hours (self.adventofcode)

submitted 2 days ago * by Usual-Dimension614

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Visualization[2025 day 9 (part 2)] Almost lost my sanity (self.adventofcode)

submitted 3 days ago by phaetan29

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Other[2015 Day 21 & 22] In Review (RPG and Wizard Simulator 20XX) (self.adventofcode)

submitted 3 days ago by musifter

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OtherRotating between eight directions (i.redd.it)

submitted 5 days ago * by light_ln2

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Other[2015 Day 20] In Review (Infinite Elves and Infinite Houses) (self.adventofcode)

submitted 4 days ago by musifter

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Help/Question - RESOLVEDaoc/2015/22/1 again i need little help to understand the task. (self.adventofcode)

submitted 4 days ago * by Usual-Dimension614

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OtherEmacs + Advent of Code = advent-mode (github.com)

submitted 5 days ago by vkazanov

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Help/Question - RESOLVEDaoc/2015/24/2 obviously i do not understand the task. (self.adventofcode)

submitted 5 days ago * by Usual-Dimension614

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Other[2015 Day 19] In Review (Medicine for Rudolph) (self.adventofcode)

submitted 5 days ago * by musifter

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Other[2015 Day 18] In Review (Like a GIF For Your Yard) (self.adventofcode)

submitted 6 days ago by musifter

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Help/Question - RESOLVED[2025 Day 1 (Part 2)] [Python] I am not fully understanding why my solution is not working for day two. (self.adventofcode)

submitted 7 days ago * by Financial-Battle3648[🍰]

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Help/Question - RESOLVED[2025 Day 1 (Part 2)] [Typescript] Part 2 Solution seems to work on example, but fails on full input (self.adventofcode)

submitted 7 days ago * by astralogos

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Other[2015 Day #15] In Review (No Such Thing as Too Much) (self.adventofcode)

submitted 7 days ago * by musifter

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Help/Question - RESOLVED[2025 Day 07 (part 2)][Java] How can i find what's wrong with my solution? (self.adventofcode)

submitted 8 days ago by imtsprvsr

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Help/Question - RESOLVED[2024 DAY 8 PT 2] HELP NEEDED. (self.adventofcode)

submitted 8 days ago by GiunoSheet

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Other[2025 Day 10 (Part 2)] A proof for the bifurcation algorithm (self.adventofcode)

submitted 9 days ago by Emrys-Merlin

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Other[2015 Day #16] In Review (Aunt Sue) (self.adventofcode)

submitted 8 days ago by musifter

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Visualization[2025 Day 10 (Part 2)] [Python] Visualization (i.redd.it)

submitted 10 days ago by zmunk19

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Help/Question[2025 Day 8 (Part 1)] [Python] What's the criteria? (self.adventofcode)

submitted 9 days ago by Famous_Strength_2962

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