--- Day 8: Haunted Wasteland ---
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.
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.
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!
After examining the maps for a bit, two nodes stick out:
AAA
andZZZ
. You feel likeAAA
is where you are now, and you have to follow the left/right instructions until you reachZZZ
.This format defines each node of the network individually. For example:
RL AAA = (BBB, CCC) BBB = (DDD, EEE) CCC = (ZZZ, GGG) DDD = (DDD, DDD) EEE = (EEE, EEE) GGG = (GGG, GGG) ZZZ = (ZZZ, ZZZ)
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 withAAA
and go right (R
) by choosing the right element ofAAA
,CCC
. Then,L
means to choose the left element ofCCC
,ZZZ
. By following the left/right instructions, you reachZZZ
in2
steps.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 meansRLRLRLRLRLRLRLRL...
and so on. For example, here is a situation that takes6
steps to reachZZZ
:LLR AAA = (BBB, BBB) BBB = (AAA, ZZZ) ZZZ = (ZZZ, ZZZ)
Starting at
AAA
, follow the left/right instructions. How many steps are required to reachZZZ
?