Day 16: The Floor Will Be Lava

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FAQ

  • Gobbel2000@feddit.de
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    11 months ago

    Rust

    I simply check each starting position individually for Part 2, I don’t know if there are more clever solutions. Initially that approach ran in 180ms which is a lot more than any of the previous puzzles needed, so I tried if I could optimize it.

    Initially I was using two hash sets, one for counting unique energized fields, and one for detecting cycles which also included the direction in the hash. Going from the default rust hasher to FxHash sped it up to 100ms. Seeing that, I thought that this point could be further improved upon, and ended up replacing both hash sets with boolean arrays, since their size is neatly bounded by the input field size. Now it runs in merely 30ms, meaning a 6x speedup just by getting rid of the hashing.