AoC has ended for the year! Congrats to everyone who participated

Here are some stats from the instance leaderboard

Top 10 Users

1. SekoiaTree
2. Leo Uino
3. Michon van Dooren
4. funnyboy-roks
5. PhiliPdB
6. jhuang97
7. Alex Utter
8. hades
9. Jindřich Ivánek
10. abclop99

Misc Stats

• 91 Users got at least 1 star
• 14 Users got 50 stars

Link to full results:

https://jeroenheijmans.github.io/advent-of-code-surveys/

Day 24: Odds

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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

Spoilers and explanation of solution:

Each vertex here is one intersection in our hike. We don't actually care about the parts in-between, because there's only one way to go. The above is a visualisation of the final path, the red edges are the edges taken. Our graph looks "like that" because it's a hiking trail, not a maze, so there's no dead ends. This took about 2 seconds to generate, due to all the cloning needed to keep track of paths. The two veeery long edges on the ends are pretty obvious choices, but one might notice that pretty much every vertex takes the two maximum paths it has, given the restrictions of the path. There's still some mildly surprising paths, such as (99, 29) -> (89, 37) with a weight of 38. I'm wondering if there's a way to dismiss more paths... This graph is actually pretty free in terms of movement.

My actual solution takes ~150 ms to run (and 8 microseconds for part one with barely any optimization, damnn)

Day 22: A Long Walk

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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

Day 22: Sand

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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

Day 21: Step

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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

Day 20: Pulse

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FAQ

• What is this?: Here is a post with a large amount of details: https://programming.dev/post/6637268
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Day 19: Aplenty

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FAQ

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Day 18: Lavaduct Lagoon

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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

Anybody got some ideas to optimize today? I've got it down to 65ms (total) on my desktop, using A* with a visitation map. Each cell in the visitation map contains (in part 2) 16 entries; 4 per direction of movement, 1 for each level of straightaway. In part 2, I use a map with 11 entries per direction.

Optimizations I've implemented:

• use a 2D array instead of a hashset/map. No idea how much this saves, I did it in the first place.
• the minimum distance for a specific cell's direction + combo applies for higher combo levels as well for part 1. For part 2, if the current combo is greater than 4, we do the same*. Gains about 70(!!) ms
• A* heuristic weighting optimization, a weight of about 1% with a manhattan distance heuristic seems to gain about 15 ms (might be my input only tho)

*Correctness-wise: the reason we're splitting by direction is because there's a difference between being at a cell going up with a 3 combo but a really short path, and going right with a 0 combo but a long path. However, this is fine because a 3 combo in the same direction as a 0 combo is identical, just more restrictive.

Optimizations that could be done but I need to ensure correctness:

the same optimization for the combo, but for directions. If I'm on a specific combo+direction, does that imply something about the distance for another direction? Simply doing the same for every non-opposite direction isn't correct

Code: https://codeberg.org/Sekoia/adventofcode/src/branch/main/src/y2023/day17.rs

Warning: quite ugly, there's like 8 copy-pastes for adding to the queue

Day 17: Clumsy Crucible

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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/
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Day 16: The Floor Will Be Lava

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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/
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Day 15: Lens Library

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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

🔒 Thread is locked until there's at least 100 2 star entries on the global leaderboard

Edit: 🔓 Unlocked

Thought I'd share mine because most of the visualisations out there show the rocks sliding one cell at a time, all together. That looks nice but for my solution that's not how it works - I walk every row/col with two cursors.

Code here: https://github.com/sjmulder/aoc/blob/master/2023/c/day14.c

The visualisation is emitted right from the solution using a small library which dumps frames to ffmpeg.

Day 14: Parabolic Reflector Dish

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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

🔒 Thread is locked until there's at least 100 2 star entries on the global leaderboard

Edit: 🔓 Unlocked

Day 13: Point of Incidence

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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/
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🔒 Thread is locked until there's at least 100 2 star entries on the global leaderboard

🔓 Unlocked

cross-posted from: https://programming.dev/post/7188393

This community still mostly has me running it and has 1 other mod but I typically like starting communities off with at least 2 mods. This community is a bit different in that theres the solution megathreads that need to be posted when a new day drops (and then unlocked when the global leaderboard fills up). When it has a dedicated mod team running it ill remove myself so its not admin run

If youre interested feel free to say so below

[email protected]

Note: to be a mod its preferred if your account is within the instance since lemmy doesnt handle cross-instance modding that well and this makes it so you have access to features added to pangora that other instances may not have

We all know and love (!) the leaderboard, but how about a different method?

One can solve a problem with a simple, naive method resulting in a short program and long runtime, or put in lots of explicit optimizations for more code and shorter runtime. (Or if you're really good, a short, fast program!)

I propose the line-second.

Take the number of lines in your program (eg, 42 lines) and the runtime (eg 0.096 seconds). Multiply these together to get a score of 4.032 line-seconds.

A smaller score is a shorter, faster program.

Similarly, (for a particular solver), a larger score is a "harder" problem.

So I managed to get part 1 of the day, but it took 2 seconds to run on the real input, which is a bad sign.

I can't see any kind of optimisation that means I can skip checks and know how many combinations are in those skipped checks (aside from 0.) I can bail out of branches of combinations if the info so far won't fit, but that still leads me to visiting every valid combination which in one of the examples is 500k. (And probably way more in the input, since if I can't complete the example near instantly the input is not happening.)

Right now I take the string, then replace the first instance of a ? with the two possible options. Check it matches the check digits so far then use recursion on those two strings.

I can try to optimise the matching, but I don't think that solves the real problem of visiting every combination.

I don't think (or hope) it's just bad code but this is my code so far (python.)

edit:

Day 12: Hot Springs

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• Code block support is not fully rolled out yet but likely will be in the middle of the event. Try to share solutions as both code blocks and using something such as https://topaz.github.io/paste/ , pastebin, or github (code blocks to future proof it for when 0.19 comes out and since code blocks currently function in some apps and some instances as well if they are running a 0.19 beta)

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

🔒 Thread is locked until there's at least 100 2 star entries on the global leaderboard

🔓 Unlocked after 25 mins