81 lines
3.0 KiB
Plaintext
81 lines
3.0 KiB
Plaintext
Advent of Code
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--- Day 7: Internet Protocol Version 7 ---
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While snooping around the local network of EBHQ, you compile a list of IP
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addresses (they're IPv7, of course; IPv6 is much too limited). You'd like to
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figure out which IPs support TLS (transport-layer snooping).
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An IP supports TLS if it has an Autonomous Bridge Bypass Annotation, or
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ABBA. An ABBA is any four-character sequence which consists of a pair of two
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different characters followed by the reverse of that pair, such as xyyx or
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abba. However, the IP also must not have an ABBA within any hypernet
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sequences, which are contained by square brackets.
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For example:
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• abba[mnop]qrst supports TLS (abba outside square brackets).
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• abcd[bddb]xyyx does not support TLS (bddb is within square brackets,
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even though xyyx is outside square brackets).
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• aaaa[qwer]tyui does not support TLS (aaaa is invalid; the interior
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characters must be different).
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• ioxxoj[asdfgh]zxcvbn supports TLS (oxxo is outside square brackets, even
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though it's within a larger string).
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How many IPs in your puzzle input support TLS?
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Your puzzle answer was 118.
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--- Part Two ---
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You would also like to know which IPs support SSL (super-secret listening).
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An IP supports SSL if it has an Area-Broadcast Accessor, or ABA, anywhere in
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the supernet sequences (outside any square bracketed sections), and a
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corresponding Byte Allocation Block, or BAB, anywhere in the hypernet
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sequences. An ABA is any three-character sequence which consists of the same
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character twice with a different character between them, such as xyx or aba.
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A corresponding BAB is the same characters but in reversed positions: yxy
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and bab, respectively.
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For example:
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• aba[bab]xyz supports SSL (aba outside square brackets with corresponding
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bab within square brackets).
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• xyx[xyx]xyx does not support SSL (xyx, but no corresponding yxy).
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• aaa[kek]eke supports SSL (eke in supernet with corresponding kek in
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hypernet; the aaa sequence is not related, because the interior character
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must be different).
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• zazbz[bzb]cdb supports SSL (zaz has no corresponding aza, but zbz has a
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corresponding bzb, even though zaz and zbz overlap).
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How many IPs in your puzzle input support SSL?
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Your puzzle answer was 260.
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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/2016/about
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. http://adventofcode.com/2016/support
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. http://adventofcode.com/2016/events
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. http://adventofcode.com/2016/settings
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. http://adventofcode.com/2016/auth/logout
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. http://adventofcode.com/2016
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. http://adventofcode.com/2016
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. http://adventofcode.com/2016/leaderboard
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. http://adventofcode.com/2016/stats
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. http://adventofcode.com/2016/sponsors
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. http://adventofcode.com/2016/sponsors
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. https://en.wikipedia.org/wiki/IP_address
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. https://en.wikipedia.org/wiki/IPv6
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. http://adventofcode.com/2016
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. http://adventofcode.com/2016/day/7/input
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