142 lines
4.1 KiB
Markdown
142 lines
4.1 KiB
Markdown
# Day 7: Laboratories
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[https://adventofcode.com/2025/day/7](https://adventofcode.com/2025/day/7)
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## Description
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### Part One
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You thank the cephalopods for the help and exit the trash compactor, finding yourself in the [familiar](https://adventofcode.com/2024/day/6) [halls](https://adventofcode.com/2018/day/4) of a North Pole research wing.
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Based on the large sign that says "teleporter hub", they seem to be researching _teleportation_; you can't help but try it for yourself and step onto the large yellow teleporter pad.
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Suddenly, you find yourself in an unfamiliar room! The room has no doors; the only way out is the teleporter. Unfortunately, the teleporter seems to be leaking [magic smoke](https://en.wikipedia.org/wiki/Magic_smoke).
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Since this is a teleporter lab, there are lots of spare parts, manuals, and diagnostic equipment lying around. After connecting one of the diagnostic tools, it helpfully displays error code `0H-N0`, which apparently 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). A tachyon beam enters the manifold at the location marked `S`; tachyon beams always move _downward_. Tachyon beams pass freely through empty space (`.`). However, if a tachyon beam encounters a splitter (`^`), the beam is stopped; instead, a new tachyon beam continues from the immediate left and from the 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` 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 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 beams, since they are both dumping tachyons into the same place between 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 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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To repair the teleporter, you first need to understand the beam-splitting properties of the tachyon manifold. In this example, a tachyon beam is 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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