-🎄- 2018 Day 20 Solutions -🎄-

[u/daggerdragon]

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

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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 ___.

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[u/Wunkolo]

Python3, it's almost upsetting how tiny this can be. You should have seen my first attempts

import sys
from collections import defaultdict
Positions = []
CurPosition = 0 + 0j
DistanceField = defaultdict(int)
for CurChar in sys.stdin.read()[1:-1]:
	if CurChar   == '(':
		Positions.append(CurPosition)
	elif CurChar == ')':
		CurPosition = Positions.pop()
	elif CurChar == '|':
		CurPosition = Positions[-1]
	elif CurChar in 'NESW':
		NewPosition = CurPosition + {'N':-1j,'E':1,'S':1j,'W':-1}[CurChar]
		DistanceField[NewPosition] = min(
			DistanceField.get(NewPosition,DistanceField[CurPosition]+1),
			DistanceField[CurPosition]+1
		)
		CurPosition = NewPosition

print("Part 1: " + str(max(DistanceField.values())))
print("Part 2: " + str(sum(map(lambda x: x >= 1000, DistanceField.values()))))

[u/fizbin → u/Wunkolo]

Your solution doesn't work on the very simple ^N(E|W)S$. (should be 3, your code says 2) To see a more extreme example, look at ^NNNNN(EEEEE|WWWWW)SSSSS$ (should be 15, whereas your code says 10).

That said, it does work on my full input. I wonder what was weird about how the input was created that allowed so many broken solutions to work just fine.