Advent Of Code

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An unofficial home for the advent of code community on programming.dev! Other challenges are also welcome!

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.

Everybody Codes is another collection of programming puzzles with seasonal events.

AoC 2025

Solution Threads

M	T	W	T	F	S	S
1	2	3	4	5	6	7
8	9	10	11	12

Rules/Guidelines

Follow the programming.dev instance rules
Keep all content related to advent of code in some way
If what youre posting relates to a day, put in brackets the year and then day number in front of the post title (e.g. [2024 Day 10])
When an event is running, keep solutions in the solution megathread to avoid the community getting spammed with posts

Relevant Communities

Relevant Links

Advent of Code Homepage

Credits

Icon base by Lorc under CC BY 3.0 with modifications to add a gradient

console.log('Hello World')

founded 2 years ago

MODERATORS

Ategon@programming.dev

Sigmatics@lemmy.ca

CameronDev@programming.dev

hades@programming.dev

🔒 - 2025 DAY 1 SOLUTIONS -🔒 (programming.dev)

submitted 3 days ago by Ategon@programming.dev to c/advent_of_code@programming.dev

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Day 1: Secret Entrance

Megathread guidelines

Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
You can send code in code blocks by using three backticks, the code, and then three backticks or use something such as https://topaz.github.io/paste/ if you prefer sending it through a URL

FAQ

What is this?: Here is a post with a large amount of details: https://programming.dev/post/6637268
Where do I participate?: https://adventofcode.com/
Is there a leaderboard for the community?: We have a programming.dev leaderboard with the info on how to join in this post: https://programming.dev/post/6631465

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[–] strlcpy@lemmy.sdf.org 11 points 2 days ago* (last edited 15 hours ago) (1 children)

DOS + BIOS boot (hybrid binary)

Repo | day01.asm | day01.c (prototype) | .COM download

Written in x86-16 assembly. Works as a DOS program but also as disk image for older PCs with BIOS support (or older VMs). Getting this setup to work was tricky, especially since when I started this, I had only basic x86-16 experience! Needless to say I've spent much time staring at hex numbers.

The very start of the file determines if it's running in DOS or as a bootloader, in which case it'll have to load the remainder of the file from disk and rearrange the memory layout to emulate the DOS situation.

Right now this is using just one segment of memory (64K). Input data is compressed using a custom run-length encoding scheme. The compressed background image is directly decoded into the VGA framebuffer, after which it is overwritten with the decompressed input file. Space is tight!

My main goal is to finish a few days at least with one or more game consoles supported (GameBoy Advance would be cool) and to do some cool palette tricks, like a day/night transition or animated water and stars.

[–] hades@programming.dev 2 points 2 days ago

so many years have passed since i last wrote a line of masm...