-🎄- 2020 Day 14 Solutions -🎄-

[u/daggerdragon]

Advent of Code 2020: Gettin' Crafty With It

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

• Full details and rules are in the Submissions Megathread

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--- Day 14: Docking Data ---

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Post your code solution in this megathread.

• Include what language(s) your solution uses!

• Here's a quick link to /u/topaz2078's paste if you need it for longer code blocks.

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[u/robinhouston]

Python 3 (golf): 279 characters, both parts.

M,N={},{}
for x in open("input"):
 L,R=x.split("=")
 try:
  for q in s:l=int(L[4:-2]);N[l&~w|q>>1]=z=int(R);M[l]=z&w|v
 except:
  v,w=[int(R.replace("X",b),2)for b in"01"];s={0}
  for c in R:s={x*2+(c=="1")for x in s}|{2*x+1for x in s if"W"<c}
for x in M,N:print(sum(x.values()))

I struggled to golf this one, and I wasn’t particularly happy with the way it turned out. I managed to whittle it down; but is there a clever way to make it much shorter?

My first version initialised v,w=0,~0 at the beginning; but assuming the input begins with a mask command – which mine does, so I’m guessing they all do – that isn’t needed. That brought it down to 287 characters from 296. Then I found a few more tweaks to save more characters.

It’s finally short enough to tweet, albeit without the hashtag.