39 lines
2.0 KiB
Markdown
Executable File
39 lines
2.0 KiB
Markdown
Executable File
## \-\-\- Day 8: Haunted Wasteland ---
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You're still riding a camel across Desert Island when you spot a sandstorm quickly approaching. When you turn to warn the Elf, she disappears before your eyes! To be fair, she had just finished warning you about _ghosts_ a few minutes ago.
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One of the camel's pouches is labeled "maps" - sure enough, it's full of documents (your puzzle input) about how to navigate the desert. At least, you're pretty sure that's what they are; one of the documents contains a list of left/right instructions, and the rest of the documents seem to describe some kind of _network_ of labeled nodes.
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It seems like you're meant to use the _left/right_ instructions to _navigate the network_. Perhaps if you have the camel follow the same instructions, you can escape the haunted wasteland!
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After examining the maps for a bit, two nodes stick out: `AAA` and `ZZZ`. You feel like `AAA` is where you are now, and you have to follow the left/right instructions until you reach `ZZZ`.
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This format defines each _node_ of the network individually. For example:
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```
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RL
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AAA = (BBB, CCC)
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BBB = (DDD, EEE)
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CCC = (ZZZ, GGG)
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DDD = (DDD, DDD)
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EEE = (EEE, EEE)
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GGG = (GGG, GGG)
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ZZZ = (ZZZ, ZZZ)
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```
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Starting with `AAA`, you need to _look up the next element_ based on the next left/right instruction in your input. In this example, start with `AAA` and go _right_ ( `R`) by choosing the right element of `AAA`, `CCC`. Then, `L` means to choose the _left_ element of `CCC`, `ZZZ`. By following the left/right instructions, you reach `ZZZ` in `2` steps.
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Of course, you might not find `ZZZ` right away. If you run out of left/right instructions, repeat the whole sequence of instructions as necessary: `RL` really means `RLRLRLRLRLRLRLRL...` and so on. For example, here is a situation that takes `6` steps to reach `ZZZ`:
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```
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LLR
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AAA = (BBB, BBB)
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BBB = (AAA, ZZZ)
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ZZZ = (ZZZ, ZZZ)
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```
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Starting at `AAA`, follow the left/right instructions. _How many steps are required to reach `ZZZ`?_ |