This will be the home for my solutions to Advent of Code 2025
Every solution will be written in lua, using the Astra lua framework.
Each solution will have its own folder in the repo
Requirements: Astra lua runtime
git clone https://github.com/Charmunks/advent-of-code-2025-lua/
cd dirname # the name of the solutions folder
astra export-bundle # optional, needed for IntelliSense/editor autocomplete
astra run main.luaAs I go, I will be writing up util functions for common things I need to do, in attempt to complete solutions faster. The most recent util file will be located at /template/utils.lua.
Current utils:
- parseFile(path): converts input txt file into an array, with each space seperated string in the input file being a value
- parseFileChar(path): converts input txt file into an array, with each character in the input file being a value
- checkMatch(value, array): checks if an array contains a value
- checkNumber(value): checks if value is a number
- checkAdj(startIndex, array, rowSize, compare): Checks if a value is adjacent to an index in a table/sheet. Includes diagonals. Think word searches
- parseNum(path) converts input txt file into an array, extracting each number
Solution 2 (/02)
The puzzle can be found here. This was a mess. At first, I completely misunderstood the question, but was able to figure it out eventually. This lost me 16 minutes though. After I figured out what it meant, implementing the functionality was fairly simple, using a lua repeat loop. In the end, it took me 23 minutes to complete part 1, but subtracting the 16 minute misunderstanding, it took me 7 minutes.
Now part 2 is where this really falls apart. Within 10 minutes I got something working on the samples, using a bunch of for loops, but it just was not working on my inputs. I spent more then 20 minutes troubleshooting, and in the end gave up (I'm doing these at midnight my time, I am tired) and looked at someone elses solution for the general logic. Now, it was a different lang so I did have to figure out how to implement it in lua, but I still feel disappointed I was not able to figure it out myself.
Solution 1 (/01)
My first advent of code solution! This one took me 40 minutes to complete. To be honest, I had literally no idea what I was doing. My first mistake was testing using my inputs instead of the sample, so I had to use the sites checker to verify my solution, which was rate limited. What I should have done, was use the sample so I could instantly verify my solution. I also didn't read the question carefully enough, and I spent a lot of time trying to figure out what the question was asking. I should have read the question carefully and then read the sample input and output to understand what the question was asking and exact values (ie I used 100 and not 99 for the overflow)
The puzzle can be found here. I initally approached the problem by subtracking/adding the total amount to change, then using math to calculate overflow. This was not working, and I got tired of trying to debug why, so I ended up just rewritting it to use a for loop to subtract/add one by one, calculating overflow the moment it went over, which proved successful. This turned out to be a better solution anyways, as it allowed me to quickly adapt my solution for problem 2 by only changing a few lines.
In the end, I learned a lot from this solution, and hope to do better in the future.