Advent of Code

I created this group last year but soon found that there was a lot more active group on programming.dev with many more participants and even a private leaderboard, so you should probably head on over there!

Happy coding everyone!

Feel free to share your solutions or browse others' for inspiration! Please tag your comments with the language you solved in to make it easier to search for specific languages in case we happen to get more comments than expected. 😀 I really hope that we can create some discussion here to liven up this community!

In preparation for this year's event I started to create a utility library and realized that I might not even need to care about decimal, or even fractional numbers, as I don't remember ever encountering them while solving a problem so far. Does anyone have any examples for problems which required using floating point calculations? Is it maybe even explicitly stated that they are not needed? (I remember that Google Code Jam had some statistical problems where the solution didn't have to be exact, just within an acceptable error margin, but that isn't likely to happen here, right?)

Advent of Code 2023 recap blog post https://dan-schreiber.com/blog/2024/1/8/advent-of-code-2023-recap. Thanks to Eric Wastl and @adventofcode for another great year. #adventofcode #adventofcode2023 #aoc

If you add tickets with the point multiplier the code is just off by one, and I spotted the problem immediately.

Hey, I've got a few solutions written in Kotlin.

• Day 1
• Day 2

What do you think?

I feel like I cheated a bit on the solution for the first day using built-in functions to search the line-string, but if it works, don't fix it I guess...

How was day one for everyone? I was surprised at how tricky it was to get the right answer for part two. Not the usual easy start I've seen in the past. I'd be interested to see any solutions here.

As a warmup for this year's Advent of Code, I'm re-reading and posting my solutions to last year's challenges. You can read, run and edit today's solution by following the post link.

Today was the final challenge for the year, and as usual was quite simple and had only one part. This involved parsing and process numbers written in what I learned was called "balanced base five" notation.

Thanks for following along, now we just need to wait a few days to see what this year holds!

As a warmup for this year's Advent of Code, I'm re-reading and posting my solutions to last year's challenges. You can read, run and edit today's solution by following the post link.

Today had us running round a maze with moving obstacles. Treating time as a dimension allowed me to build a graph and find the shortest path. Part 2 just required doing this three times. This took me closer than I like to a full second runtime, but not close enough to make me re-think my solution.

As a warmup for this year's Advent of Code, I'm re-reading and posting my solutions to last year's challenges. You can read, run and edit today's solution by following the post link.

Today was a kinda variant of Conway's Game of Life: we had to move elves around according to a set of rules while avoiding collisions and observe the size of the bounding box after 10 rounds. Part 2 asked us to run until the pattern stagnated. Nothing clever in my solution as most of the challenge seemed to be in understanding the rules correctly :-)

As a warmup for this year's Advent of Code, I'm re-reading and posting my solutions to last year's challenges. You can read, run and edit today's solution by following the post link.

Today started quite easily: build a map and then follow some directions to navigate around it. Part 2? The map is now wrapped around a cube. Oof. I dealt with it by setting up logic for an "ideal" cube layout, and then mapping the provided definition onto that. Oddly, my solution for part2 seems to run faster than part1 despite all the added complexity...

As a warmup for this year's Advent of Code, I'm re-reading and posting my solutions to last year's challenges. You can read, run and edit today's solution by following the post link.

Today was again quite an easy one, requiring us to build up a tree of values and operations on those values. Part 1 had us evaluate the root value, and part 2 required us to change the value of a specific node to ensure that both branches below the root node evaluated to the same value. The linear nature of the operations allowed me to just try two different values and then interpolate the correct answer.

As a warmup for this year's Advent of Code, I'm re-reading and posting my solutions to last year's challenges. You can read, run and edit today's solution by following the post link.

Today came as a welcome relief after two tricky days! We had to jumble a file according to some simple rules. The biggest challenge was interpreting the instructions correctly; the solution itself took only a few lines. Part two just added a key and increased the number of iterations. My original approach still ran in under a second (0.7s) so I didn't bother looking into it any further, and just enjoyed the free time :-)

As a warmup for this year's Advent of Code, I'm re-reading and posting my solutions to last year's challenges. You can read, run and edit today's solution by following the post link.

Today was a sudden increase in difficulty (for me anyway). We had to find the best route for opening a system of valves to maximise the total flow through the network. Part two repeated the exercise, but with the addition of a friendly elephant to help with the work.

I was able to simplify the network enough to solve part 1 in a reasonable time, but had to hack my solution for part 2 terribly to get it under a second. Reading some other solutions, I missed out on some key approaches including pre-calculating minimum paths between all pairs of valves (e.g. using the Floyd–Warshall algorithm), aggressive caching of intermediate states, and separating out my movements from the elephant's movements.

Go and read @[email protected]'s Clojure solution for a much more thoughtful approach :smile:

As a warmup for this year's Advent of Code, I'm re-reading and posting my solutions to last year's challenges. You can read, run and edit today's solution by following the post link.

Today had us finding the surface area of a cluster of cubes, first in total, then excluding any internal voids. Nice and easy compared to the last couple of days!

As a warmup for this year's Advent of Code, I'm re-reading and posting my solutions to last year's challenges. You can read, run and edit today's solution by following the post link.

Today's challenge had us building a simple Tetris clone with the additional twist that a regular sequence of jets of air blow the falling pieces sideways. Part two asked us to model this for a bazillion cycles, so we needed to keep an eye on the pattern of landed blocks and look for the same pattern to repeat.

As a warmup for this year's Advent of Code, I'm re-reading and posting my solutions to last year's challenges. You can read, run and edit today's solution by following the post link.

Today we had to monitor and manage flow through a network of valves. The second part added a friendly elephant to help. So for me it was about building a weighted graph and then milling around it looking for good solutions. Despite my chaotic approach and somewhat ugly code, my solution ended up being impressively fast.

As a warmup for this year's Advent of Code, I'm re-reading and posting my solutions to last year's challenges. You can read, run and edit today's solution by following the post link.

Today we were given the output of a set of sensors recording the locations of their nearest beacons, and were asked to derive more information about those beacons. This was made much simpler due to the odd way these beacons' signal propagated, involving tracking diagonal lines rather than doing any trig. Part 2 required a bit of lateral thinking to avoid an overly-slow solution.

The 2023 event starts in december, I'll try it in Rust. What are the posts about Nadvent of code and where can I find the tasks?