99 lines
3.8 KiB
Plaintext
99 lines
3.8 KiB
Plaintext
Advent of Code
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--- Day 9: Explosives in Cyberspace ---
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Wandering around a secure area, you come across a datalink port to a new
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part of the network. After briefly scanning it for interesting files, you
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find one file in particular that catches your attention. It's compressed
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with an experimental format, but fortunately, the documentation for the
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format is nearby.
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The format compresses a sequence of characters. Whitespace is ignored. To
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indicate that some sequence should be repeated, a marker is added to the
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file, like (10x2). To decompress this marker, take the subsequent 10
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characters and repeat them 2 times. Then, continue reading the file after
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the repeated data. The marker itself is not included in the decompressed
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output.
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If parentheses or other characters appear within the data referenced by a
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marker, that's okay - treat it like normal data, not a marker, and then
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resume looking for markers after the decompressed section.
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For example:
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• ADVENT contains no markers and decompresses to itself with no changes,
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resulting in a decompressed length of 6.
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• A(1x5)BC repeats only the B a total of 5 times, becoming ABBBBBC for a
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decompressed length of 7.
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• (3x3)XYZ becomes XYZXYZXYZ for a decompressed length of 9.
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• A(2x2)BCD(2x2)EFG doubles the BC and EF, becoming ABCBCDEFEFG for a
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decompressed length of 11.
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• (6x1)(1x3)A simply becomes (1x3)A - the (1x3) looks like a marker, but
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because it's within a data section of another marker, it is not treated
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any differently from the A that comes after it. It has a decompressed
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length of 6.
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• X(8x2)(3x3)ABCY becomes X(3x3)ABC(3x3)ABCY (for a decompressed length of
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18), because the decompressed data from the (8x2) marker (the (3x3)ABC) is
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skipped and not processed further.
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What is the decompressed length of the file (your puzzle input)? Don't count
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whitespace.
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Your puzzle answer was 110346.
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--- Part Two ---
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Apparently, the file actually uses version two of the format.
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In version two, the only difference is that markers within decompressed data
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are decompressed. This, the documentation explains, provides much more
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substantial compression capabilities, allowing many-gigabyte files to be
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stored in only a few kilobytes.
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For example:
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• (3x3)XYZ still becomes XYZXYZXYZ, as the decompressed section contains
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no markers.
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• X(8x2)(3x3)ABCY becomes XABCABCABCABCABCABCY, because the decompressed
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data from the (8x2) marker is then further decompressed, thus triggering
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the (3x3) marker twice for a total of six ABC sequences.
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• (27x12)(20x12)(13x14)(7x10)(1x12)A decompresses into a string of A
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repeated 241920 times.
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• (25x3)(3x3)ABC(2x3)XY(5x2)PQRSTX(18x9)(3x2)TWO(5x7)SEVEN becomes 445
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characters long.
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Unfortunately, the computer you brought probably doesn't have enough memory
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to actually decompress the file; you'll have to come up with another way to
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get its decompressed length.
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What is the decompressed length of the file using this improved format?
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Although it hasn't changed, you can still get your puzzle input.
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Your puzzle answer was 10774309173.
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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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. http://adventofcode.com/2016/day/9/input
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