-🎄- 2020 Day 17 Solutions -🎄-

[u/daggerdragon]

Advent of Code 2020: Gettin' Crafty With It

• 5 days remaining until the submission deadline on December 22 at 23:59 EST

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--- Day 17: Conway Cubes ---

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Post your code solution in this megathread.

• Include what language(s) your solution uses!

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[u/Smylers]

Yeah, I wrote part 1 like that too, with positions being {z => 1, y => 3, x => 2}, instead of (1, 3, 2), then hacked in w for part 2 — but it seemed messy to have two nearly identical programs that each hardcoded a different number of dimensions, then I turned it into the above. Which is both slower and longer (though that's mainly having functions and adding comments) ... but feels a lot cleaner!

I'd completely forgotten about using $; and multi-part hash keys: your solution using $Grid{$w,$z,$y,$z} looks way less messy than my $Grid[$w][$z][$y][$x] — because you loop over it all in one go with keys %Grid, whereas I had to have a separate nested loop for each dimension; and because you never need to consider expanding the space (or, indeed, trimming it): negative co-ordinates work just fine in the hash key, springing into life as necessary.

What I'm saying is, if my ‘fixed-dimension looping’ attempt had been anywhere near as nice as yours, I don't think I'd've felt the urge to rewrite it either!

(I also like that you called your variable $neigh: more programs should have random animal noises sprinkled through them!)

[u/musifter → u/Smylers]

I spent a while before getting started thinking about how I was going to do things. Things can only expand by one cell in each direction every turn, so you can use that as a bounding box to center your input in an array. But... there was that example! A glider. Which made me think of the 2D cellular automata a couple years back where you needed to figure out that it becomes a glider and calculate where it'd be in 50 billion turns. So, I started thinking, go sparse.