275 lines
7.2 KiB
Plaintext
275 lines
7.2 KiB
Plaintext
Advent of Code
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br0xen [7](AoC++) 14*
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--- Day 7: Laboratories ---
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You thank the cephalopods for the help and exit the trash compactor,
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finding yourself in the [16]familiar [17]halls of a North Pole research
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wing.
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Based on the large sign that says "teleporter hub", they seem to be
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researching teleportation; you can't help but try it for yourself and step
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onto the large yellow teleporter pad.
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Suddenly, you find yourself in an unfamiliar room! The room has no doors;
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the only way out is the teleporter. Unfortunately, the teleporter seems to
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be leaking [18]magic smoke.
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Since this is a teleporter lab, there are lots of spare parts, manuals,
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and diagnostic equipment lying around. After connecting one of the
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diagnostic tools, it helpfully displays error code 0H-N0, which apparently
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means that there's an issue with one of the tachyon manifolds.
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You quickly locate a diagram of the tachyon manifold (your puzzle input).
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A tachyon beam enters the manifold at the location marked S; tachyon beams
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always move downward. Tachyon beams pass freely through empty space (.).
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However, if a tachyon beam encounters a splitter (^), the beam is stopped;
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instead, a new tachyon beam continues from the immediate left and from the
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immediate right of the splitter.
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For example:
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.......S.......
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...............
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.......^.......
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...............
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......^.^......
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...............
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.....^.^.^.....
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...............
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....^.^...^....
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...............
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...^.^...^.^...
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...............
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..^...^.....^..
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...............
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.^.^.^.^.^...^.
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...............
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In this example, the incoming tachyon beam (|) extends downward from S
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until it reaches the first splitter:
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.......S.......
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.......|.......
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.......^.......
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...............
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......^.^......
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...............
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.....^.^.^.....
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...............
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....^.^...^....
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...............
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...^.^...^.^...
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...............
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..^...^.....^..
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...............
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.^.^.^.^.^...^.
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...............
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At that point, the original beam stops, and two new beams are emitted from
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the splitter:
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.......S.......
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.......|.......
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......|^|......
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...............
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......^.^......
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...............
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.....^.^.^.....
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...............
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....^.^...^....
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...............
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...^.^...^.^...
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...............
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..^...^.....^..
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...............
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.^.^.^.^.^...^.
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...............
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Those beams continue downward until they reach more splitters:
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.......S.......
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.......|.......
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......|^|......
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......|.|......
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......^.^......
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...............
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.....^.^.^.....
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...............
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....^.^...^....
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...............
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...^.^...^.^...
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...............
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..^...^.....^..
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...............
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.^.^.^.^.^...^.
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...............
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At this point, the two splitters create a total of only three tachyon
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beams, since they are both dumping tachyons into the same place between
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them:
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.......S.......
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.......|.......
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......|^|......
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......|.|......
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.....|^|^|.....
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...............
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.....^.^.^.....
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...............
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....^.^...^....
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...............
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...^.^...^.^...
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...............
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..^...^.....^..
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...............
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.^.^.^.^.^...^.
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...............
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This process continues until all of the tachyon beams reach a splitter or
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exit the manifold:
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.......S.......
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.......|.......
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......|^|......
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......|.|......
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.....|^|^|.....
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.....|.|.|.....
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....|^|^|^|....
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....|.|.|.|....
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...|^|^|||^|...
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...|.|.|||.|...
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..|^|^|||^|^|..
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..|.|.|||.|.|..
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.|^|||^||.||^|.
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.|.|||.||.||.|.
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|^|^|^|^|^|||^|
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|.|.|.|.|.|||.|
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To repair the teleporter, you first need to understand the beam-splitting
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properties of the tachyon manifold. In this example, a tachyon beam is
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split a total of 21 times.
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Analyze your manifold diagram. How many times will the beam be split?
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Your puzzle answer was 1600.
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--- Part Two ---
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With your analysis of the manifold complete, you begin fixing the
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teleporter. However, as you open the side of the teleporter to replace the
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broken manifold, you are surprised to discover that it isn't a classical
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tachyon manifold - it's a quantum tachyon manifold.
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With a quantum tachyon manifold, only a single tachyon particle is sent
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through the manifold. A tachyon particle takes both the left and right
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path of each splitter encountered.
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Since this is impossible, the manual recommends the many-worlds
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interpretation of quantum tachyon splitting: each time a particle reaches
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a splitter, it's actually time itself which splits. In one timeline, the
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particle went left, and in the other timeline, the particle went right.
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To fix the manifold, what you really need to know is the number of
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timelines active after a single particle completes all of its possible
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journeys through the manifold.
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In the above example, there are many timelines. For instance, there's the
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timeline where the particle always went left:
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.......S.......
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.......|.......
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......|^.......
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......|........
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.....|^.^......
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.....|.........
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....|^.^.^.....
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....|..........
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...|^.^...^....
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...|...........
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..|^.^...^.^...
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..|............
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.|^...^.....^..
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.|.............
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|^.^.^.^.^...^.
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|..............
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Or, there's the timeline where the particle alternated going left and
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right at each splitter:
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.......S.......
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.......|.......
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......|^.......
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......|........
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......^|^......
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.......|.......
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.....^|^.^.....
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......|........
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....^.^|..^....
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.......|.......
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...^.^.|.^.^...
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.......|.......
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..^...^|....^..
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.......|.......
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.^.^.^|^.^...^.
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......|........
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Or, there's the timeline where the particle ends up at the same point as
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the alternating timeline, but takes a totally different path to get there:
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.......S.......
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.......|.......
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......|^.......
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......|........
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.....|^.^......
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.....|.........
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....|^.^.^.....
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....|..........
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....^|^...^....
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.....|.........
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...^.^|..^.^...
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......|........
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..^..|^.....^..
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.....|.........
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.^.^.^|^.^...^.
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......|........
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In this example, in total, the particle ends up on 40 different timelines.
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Apply the many-worlds interpretation of quantum tachyon splitting to your
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manifold diagram. In total, how many different timelines would a single
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tachyon particle end up on?
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Your puzzle answer was 8632253783011.
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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 [19]return to your Advent calendar and try
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another puzzle.
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If you still want to see it, you can [20]get your puzzle input.
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References
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Visible links
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1. https://adventofcode.com/
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2. https://adventofcode.com/2025/about
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3. https://adventofcode.com/2025/events
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4. https://adventofcode.com/2025/shop
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5. https://adventofcode.com/2025/settings
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6. https://adventofcode.com/2025/auth/logout
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7. Advent of Code Supporter
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https://adventofcode.com/2025/support
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8. https://adventofcode.com/2025
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9. https://adventofcode.com/2025
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10. https://adventofcode.com/2025/support
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11. https://adventofcode.com/2025/sponsors
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12. https://adventofcode.com/2025/leaderboard/private
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13. https://adventofcode.com/2025/stats
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14. https://adventofcode.com/2025/sponsors
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16. https://adventofcode.com/2024/day/6
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17. https://adventofcode.com/2018/day/4
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18. https://en.wikipedia.org/wiki/Magic_smoke
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19. https://adventofcode.com/2025
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20. https://adventofcode.com/2025/day/7/input
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