71 lines
3.7 KiB
Plaintext
71 lines
3.7 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 part of the network. After briefly scanning it for
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interesting files, you find one file in particular that catches your attention. It's compressed with an experimental format, but
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fortunately, the documentation for the format is nearby.
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The format compresses a sequence of characters. Whitespace is ignored. To indicate that some sequence should be repeated, a marker is
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added to the file, like (10x2). To decompress this marker, take the subsequent 10 characters and repeat them 2 times. Then, continue
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reading the file after the repeated data. The marker itself is not included in the decompressed output.
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If parentheses or other characters appear within the data referenced by a marker, that's okay - treat it like normal data, not a
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marker, and then 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, 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 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 decompressed length of 11.
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• (6x1)(1x3)A simply becomes (1x3)A - the (1x3) looks like a marker, but because it's within a data section of another marker, it
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is not treated any differently from the A that comes after it. It has a decompressed length of 6.
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• X(8x2)(3x3)ABCY becomes X(3x3)ABC(3x3)ABCY (for a decompressed length of 18), because the decompressed data from the (8x2) marker
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(the (3x3)ABC) is skipped and not processed further.
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What is the decompressed length of the file (your puzzle input)? Don't count whitespace.
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Your puzzle answer was __________.
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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 are decompressed. This, the documentation explains,
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provides much more substantial compression capabilities, allowing many-gigabyte files to be 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 no markers.
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• X(8x2)(3x3)ABCY becomes XABCABCABCABCABCABCY, because the decompressed data from the (8x2) marker is then further decompressed,
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thus triggering 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 repeated 241920 times.
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• (25x3)(3x3)ABC(2x3)XY(5x2)PQRSTX(18x9)(3x2)TWO(5x7)SEVEN becomes 445 characters long.
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Unfortunately, the computer you brought probably doesn't have enough memory to actually decompress the file; you'll have to come up
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with another way to 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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Answer: _____________________ [ [Submit] ]
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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/day/9/input
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