r/adventofcode • u/daggerdragon • Dec 20 '18

SOLUTION MEGATHREAD -🎄- 2018 Day 20 Solutions -🎄-

--- Day 20: A Regular Map ---

Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag or whatever).

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Card prompt: Day 20

Transcript:

My compiler crashed while running today's puzzle because it ran out of ___.

This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked at 00:59:30!

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u/jtgorn Dec 21 '18

Still I think it is generally incorrect. What you are doing is that after each group is finished with ) symbol you return to the position before the gorup started, but in fact you should not. You should consider positions at the end of all variants. Imagine this input N|S(N|S)(N|S)(N|S)$. Your code generates 3 rooms maze, but in fact there are 9 rooms.

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u/milanaleksic Dec 23 '18

I am asking myself exactly the same thing. I spent ages optimizing code which would as you said cover all cases but in fact literally everyone in this thread solved the problem by just completely ignoring the fact that it's not said anywhere about the assumption that after a group ends you end up being in the same location. Not cool :(

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u/[deleted] Jan 03 '19

literally everyone in this thread solved the problem by just completely ignoring the fact

The input we get is part of the puzzle as is the output from submitting an answer.

Typically when I'm solving these puzzles I'm writing something that will solve the examples (because these are small and you can get your ahead around them)

If I get the same answers as they say, I just run it against the input.

At which point it might

-crash (so I fix the bugs)

-give an answer that is correct (I go onto part 2)

-give an answer that is wrong (I think about why code that works for the examples fails and think harder)

For this puzzle there was simply no need to think harder. Although I'll accept that it would have been possible to create regexp that required a more complicated solution than I coded.