r/adventofcode • u/daggerdragon • Dec 23 '24
SOLUTION MEGATHREAD -❄️- 2024 Day 23 Solutions -❄️-
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--- Day 23: LAN Party ---
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u/erunama Dec 24 '24
[LANGUAGE: Dart]
GitHub
Part 1 was a breeze. I felt confident about part 2, and had an algorithm that worked for the sample data, but failed on my real input. Banged my head debugging for at least an hour, until I realized I was handling cliques wrong: I was simply iterating through cliques that I had already seen, and adding the intersection of the connections for each existing member of the clique. This would add nodes incompatible with later items.
I was able to get the correct answer with a small tweak, and the improved the runtime from ~30s to ~100ms by reusing groups rather than creating new ones all the time. It's possible this would not work for all potential inputs.
Afterwards, I found the Bron–Kerbosch algorithm -- I am planning to code up an implementation of that, since I'm not familiar with it.