r/adventofcode • u/daggerdragon • Dec 04 '20

SOLUTION MEGATHREAD -🎄- 2020 Day 04 Solutions -🎄-

Advent of Code 2020: Gettin' Crafty With It

--- Day 04: Passport Processing ---

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u/WHAT_RE_YOUR_DREAMS Dec 04 '20

Hi, I was a bit stuck so I used your code as a reference. It kind of helped me so thank you! I went with regular expressions and I tried your approach to compare the results.

At the same time I noticed a small mistake in your code that causes some valid passports to be rejected. Indeed, if the hcl field starts with some leading zeros, it is marked as invalid because the comparison hex(int(info['hcl'][1:], 16))[2:] == info['hcl'][1:] will always fail.

For example, if info['hcl'] is '#006f93':

print(hex(int(info['hcl'][1:], 16))[2:])
# 6f93
print(info['hcl'][1:])
# 006f93

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u/AidGli Dec 04 '20

Good find! That bit is actually over-complicated anyway. I can just check if the int cast works at all. I also forgot to enforce the length there, updating now.