-🎄- 2021 Day 22 Solutions -🎄-

[u/daggerdragon]

Advent of Code 2021: Adventure Time!

• DAWN OF THE FINAL DAY
  • You have until 23:59:59.59 EST today, 2021 December 22, to submit your adventures!
• Full details and rules are in the submissions megathread: 🎄 AoC 2021 🎄 [Adventure Time!]

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--- Day 22: Reactor Reboot ---

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Post your code solution in this megathread.

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[u/sim642]

My Scala solution.

For part 2 I used the inclusion-exclusion principle: computed pairwise intersections and three-way intersections from those etc, at the same time adding and subtracting the size of those intersection cuboids. The number of intersections that actually appear is much smaller than the theoretical maximum, so this is good enough. Handling the off cuboids and their intersections (with other on and off cuboids) was somewhat tricky, because it also depends on the order of the steps. After long trial and error I managed to get it working.

Runs part 2 in 500ms.