76 lines
2.6 KiB
Plaintext
76 lines
2.6 KiB
Plaintext
Advent of Code
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--- Day 11: Corporate Policy ---
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Santa's previous password expired, and he needs help choosing a new one.
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To help him remember his new password after the old one expires, Santa has
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devised a method of coming up with a password based on the previous one.
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Corporate policy dictates that passwords must be exactly eight lowercase
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letters (for security reasons), so he finds his new password by incrementing
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his old password string repeatedly until it is valid.
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Incrementing is just like counting with numbers: xx, xy, xz, ya, yb, and so
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on. Increase the rightmost letter one step; if it was z, it wraps around to
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a, and repeat with the next letter to the left until one doesn't wrap
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around.
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Unfortunately for Santa, a new Security-Elf recently started, and he has
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imposed some additional password requirements:
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• Passwords must include one increasing straight of at least three
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letters, like abc, bcd, cde, and so on, up to xyz. They cannot skip
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letters; abd doesn't count.
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• Passwords may not contain the letters i, o, or l, as these letters can
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be mistaken for other characters and are therefore confusing.
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• Passwords must contain at least two different, non-overlapping pairs of
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letters, like aa, bb, or zz.
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For example:
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• hijklmmn meets the first requirement (because it contains the straight
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hij) but fails the second requirement requirement (because it contains i
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and l).
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• abbceffg meets the third requirement (because it repeats bb and ff) but
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fails the first requirement.
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• abbcegjk fails the third requirement, because it only has one double
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letter (bb).
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• The next password after abcdefgh is abcdffaa.
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• The next password after ghijklmn is ghjaabcc, because you eventually
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skip all the passwords that start with ghi..., since i is not allowed.
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Given Santa's current password (your puzzle input), what should his next
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password be?
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Your puzzle answer was hepxxyzz.
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--- Part Two ---
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Santa's password expired again. What's the next one?
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Your puzzle answer was heqaabcc.
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Both parts of this puzzle are complete! They provide two gold stars: **
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At this point, you should return to your advent calendar and try another
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puzzle.
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Your puzzle input was hepxcrrq.
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References
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Visible links
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. http://adventofcode.com/
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. http://adventofcode.com/about
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. http://adventofcode.com/stats
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. http://adventofcode.com/leaderboard
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. http://adventofcode.com/settings
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. http://adventofcode.com/auth/logout
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. http://adventofcode.com/
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