gerikson

Principal Skinner moment

"Did I miscopy the input?"

"No, it is my algorithm that is wrong"

kinda satisfying to figure out I was correct all along.

Part 2 is not as fast as I'd like (14s), but faster than it was. People on reddit are wittering on about search trees, me I just sling Perl hashrefs around

https://github.com/gustafe/aoc2024/blob/main/d09-Disk-Fragmenter.pl

Eric added some 0s in the grid which fucked up my existence code, sneaky devil

thanks for the tip, I looked into it again and I found I was cutting in the wrong place. Fixed now, and halves the time for part 2

same here, I was dicking around with combinatorics to get all combos of plus and multiply but realized before I got to the end it was gonna take too long. Then I figured that a DFS was the way to go.

I tried to optimize a bit by exiting early if the cumulative result became too large, but for some reason that gave me incorrect (too low) answers. Part 2 runs in around 1 min anyway.

https://github.com/gustafe/aoc2024/blob/main/d07-Bridge-Repair.pl

I also brute-forced this. I figured there's a bit optimization to be done if you "draw a line" to the next obstacle instead of going step by step, and also maybe exclude some areas, but in the end I just set an exit value to break if the number of steps exceeded a certain value and say that was a loop. Took almost 20m but a star is a star.

update I only added obstructions in the original path, which cut the time down to 5 minutes or so.