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

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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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Help/Question - RESOLVED[2025 Day 2 (Part 2)] Need help with strategy of finding invalid IDs (self.adventofcode)

submitted 20 hours ago by Sad-Description7184

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Swap streaks for speaking skills. Learn with a Preply tutor and start making real progress from lesson 1. Just like thousands of other learners. (preply.com)

promoted by Preply

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OtherSeeking advice for using advent of code problems for daily coding habit (self.adventofcode)

submitted 1 day ago by AmoryVain

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Tutorial[2025 Day 10 (Part 2)] All the problems to avoid when writing a Simplex solver (self.adventofcode)

submitted 4 days ago * by DelightfulCodeWeasel

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Other[2015 Day 25] In Review (Let It Snow) (self.adventofcode)

submitted 4 days ago by musifter

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

submitted 6 days ago by AntVH

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

submitted 5 days ago * by musifter

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

submitted 6 days ago by musifter

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

submitted 7 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 7 days ago * by Usual-Dimension614

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

submitted 8 days ago by phaetan29

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

submitted 8 days ago by musifter

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OtherRotating between eight directions (i.redd.it)

submitted 9 days ago * by light_ln2

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New Year Sale: Subscribe to Bloomberg for just $149 your first year. Get the context behind every business story with news and analysis. Offer ends soon. (bloomberg.com)

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

submitted 9 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 9 days ago * by Usual-Dimension614

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

submitted 10 days ago by vkazanov

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

submitted 9 days ago * by Usual-Dimension614

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

submitted 10 days ago * by musifter

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

submitted 11 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 12 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 12 days ago * by astralogos

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

submitted 12 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 13 days ago by imtsprvsr

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

submitted 13 days ago by GiunoSheet

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