93 lines
4.0 KiB
Plaintext
93 lines
4.0 KiB
Plaintext
Advent of Code
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--- Day 15: Timing is Everything ---
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The halls open into an interior plaza containing a large kinetic sculpture.
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The sculpture is in a sealed enclosure and seems to involve a set of
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identical spherical capsules that are carried to the top and allowed to
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bounce through the maze of spinning pieces.
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Part of the sculpture is even interactive! When a button is pressed, a
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capsule is dropped and tries to fall through slots in a set of rotating
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discs to finally go through a little hole at the bottom and come out of the
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sculpture. If any of the slots aren't aligned with the capsule as it passes,
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the capsule bounces off the disc and soars away. You feel compelled to get
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one of those capsules.
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The discs pause their motion each second and come in different sizes; they
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seem to each have a fixed number of positions at which they stop. You decide
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to call the position with the slot 0, and count up for each position it
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reaches next.
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Furthermore, the discs are spaced out so that after you push the button, one
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second elapses before the first disc is reached, and one second elapses as
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the capsule passes from one disk to the one below it. So, if you push the
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button at time=100, then the capsule reaches the top disc at time=101, the
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second disc at time=102, the third disc at time=103, and so on.
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The button will only drop a capsule at an integer time - no fractional
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seconds allowed.
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For example, at time=0, suppose you see the following arrangement:
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Disc #1 has 5 positions; at time=0, it is at position 4.
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Disc #2 has 2 positions; at time=0, it is at position 1.
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If you press the button exactly at time=0, the capsule would start to fall;
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it would reach the first disc at time=1. Since the first disc was at
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position 4 at time=0, by time=1 it has ticked one position forward. As a
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five-position disc, the next position is 0, and the capsule falls through
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the slot.
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Then, at time=2, the capsule reaches the second disc. The second disc has
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ticked forward two positions at this point: it started at position 1, then
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continued to position 0, and finally ended up at position 1 again. Because
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there's only a slot at position 0, the capsule bounces away.
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If, however, you wait until time=5 to push the button, then when the capsule
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reaches each disc, the first disc will have ticked forward 5+1 = 6 times (to
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position 0), and the second disc will have ticked forward 5+2 = 7 times
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(also to position 0). In this case, the capsule would fall through the discs
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and come out of the machine.
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However, your situation has more than two discs; you've noted their
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positions in your puzzle input. What is the first time you can press the
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button to get a capsule?
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Your puzzle answer was 400589.
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--- Part Two ---
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After getting the first capsule (it contained a star! what great fortune!),
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the machine detects your success and begins to rearrange itself.
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When it's done, the discs are back in their original configuration as if it
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were time=0 again, but a new disc with 11 positions and starting at position
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0 has appeared exactly one second below the previously-bottom disc.
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With this new disc, and counting again starting from time=0 with the
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configuration in your puzzle input, what is the first time you can press the
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button to get another capsule?
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Although it hasn't changed, you can still get your puzzle input.
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Answer: 3045959
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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://youtu.be/IxDoO9oODOk?t=177
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. http://adventofcode.com/2016/day/15/input
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