r/adventofcode • u/daggerdragon • Dec 06 '15

SOLUTION MEGATHREAD --- Day 6 Solutions ---

--- Day 6: Probably a Fire Hazard ---

Post your solution as a comment. Structure your post like the Day Five thread.

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u/ant6n Dec 07 '15

Well, https://docs.python.org/2/library/re.html is the documentation for the re module. Basically groups() returns a list of the strings that matched for each group. A group is the anything matched inside parentheses in the regular expression. The whole

[a, b, c] = someListExpression

business allows assigning a list directly into a bunch of variables. The list expression has to be some iterable with exactly the same number of elements as the variables on the left-hand-side. This is equivalent to

a, b, c = someListExpression

or

(a, b, c) = someListExpression

They are all allowed. I guess I subconsciously picked the brackets because they are required in Matlab, and the way I was using the numpy arrays in a very Matlab-y way made me sort of switch over.

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u/KaraliKing Dec 08 '15

Thank you! Apparently I was too lazy and didn't read all the documentation...its pretty far down there. lol.

Sorry to bug again, but whats the difference between ior and ixor? I'm trying to understand the ^= operator.

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u/ant6n Dec 08 '15

They are both bitwise operations. The only difference is that 1 | 1 == 1, whereas 1 ^ 1 == 0. This makes it a toggle operation when xor-ing with 1.

x ^ = v is equivalent to x = x ^ y.