56 lines
1.9 KiB
Plaintext
56 lines
1.9 KiB
Plaintext
Advent of Code
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--- Day 10: Elves Look, Elves Say ---
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Today, the Elves are playing a game called look-and-say. They take turns
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making sequences by reading aloud the previous sequence and using that
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reading as the next sequence. For example, 211 is read as "one two, two
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ones", which becomes 1221 (1 2, 2 1s).
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Look-and-say sequences are generated iteratively, using the previous value
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as input for the next step. For each step, take the previous value, and
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replace each run of digits (like 111) with the number of digits (3) followed
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by the digit itself (1).
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For example:
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• 1 becomes 11 (1 copy of digit 1).
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• 11 becomes 21 (2 copies of digit 1).
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• 21 becomes 1211 (one 2 followed by one 1).
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• 1211 becomes 111221 (one 1, one 2, and two 1s).
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• 111221 becomes 312211 (three 1s, two 2s, and one 1).
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Starting with the digits in your puzzle input, apply this process 40 times.
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What is the length of the result?
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Your puzzle answer was 360154.
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--- Part Two ---
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Neat, right? You might also enjoy hearing John Conway talking about this
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sequence (that's Conway of Conway's Game of Life fame).
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Now, starting again with the digits in your puzzle input, apply this process
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50 times. What is the length of the new result?
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Your puzzle answer was 5103798.
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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 puzzle.
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Your puzzle input was 1113122113.
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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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. https://en.wikipedia.org/wiki/Look-and-say_sequence
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. https://www.youtube.com/watch?v=ea7lJkEhytA
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. http://adventofcode.com/
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