223 lines
7.7 KiB
Plaintext
223 lines
7.7 KiB
Plaintext
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Advent of Code
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--- Day 11: Radioisotope Thermoelectric Generators ---
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You come upon a column of four floors that have been entirely sealed off
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from the rest of the building except for a small dedicated lobby. There are
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some radiation warnings and a big sign which reads "Radioisotope Testing
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Facility".
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According to the project status board, this facility is currently being used
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to experiment with Radioisotope Thermoelectric Generators (RTGs, or simply
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"generators") that are designed to be paired with specially-constructed
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microchips. Basically, an RTG is a highly radioactive rock that generates
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electricity through heat.
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The experimental RTGs have poor radiation containment, so they're
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dangerously radioactive. The chips are prototypes and don't have normal
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radiation shielding, but they do have the ability to generate an
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electromagnetic radiation shield when powered. Unfortunately, they can only
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be powered by their corresponding RTG. An RTG powering a microchip is still
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dangerous to other microchips.
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In other words, if a chip is ever left in the same area as another RTG, and
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it's not connected to its own RTG, the chip will be fried. Therefore, it is
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assumed that you will follow procedure and keep chips connected to their
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corresponding RTG when they're in the same room, and away from other RTGs
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otherwise.
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These microchips sound very interesting and useful to your current
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activities, and you'd like to try to retrieve them. The fourth floor of the
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facility has an assembling machine which can make a self-contained, shielded
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computer for you to take with you - that is, if you can bring it all of the
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RTGs and microchips.
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Within the radiation-shielded part of the facility (in which it's safe to
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have these pre-assembly RTGs), there is an elevator that can move between
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the four floors. Its capacity rating means it can carry at most yourself and
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two RTGs or microchips in any combination. (They're rigged to some heavy
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diagnostic equipment - the assembling machine will detach it for you.) As a
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security measure, the elevator will only function if it contains at least
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one RTG or microchip. The elevator always stops on each floor to recharge,
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and this takes long enough that the items within it and the items on that
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floor can irradiate each other. (You can prevent this if a Microchip and its
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Generator end up on the same floor in this way, as they can be connected
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while the elevator is recharging.)
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You make some notes of the locations of each component of interest (your
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puzzle input). Before you don a hazmat suit and start moving things around,
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you'd like to have an idea of what you need to do.
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When you enter the containment area, you and the elevator will start on the
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first floor.
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For example, suppose the isolated area has the following arrangement:
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The first floor contains a hydrogen-compatible microchip and a
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lithium-compatible microchip.
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The second floor contains a hydrogen generator.
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The third floor contains a lithium generator.
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The fourth floor contains nothing relevant.
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As a diagram (F# for a Floor number, E for Elevator, H for Hydrogen, L for
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Lithium, M for Microchip, and G for Generator), the initial state looks like
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this:
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F4 . . . . .
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F3 . . . LG .
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F2 . HG . . .
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F1 E . HM . LM
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Then, to get everything up to the assembling machine on the fourth floor,
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the following steps could be taken:
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• Bring the Hydrogen-compatible Microchip to the second floor, which is
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safe because it can get power from the Hydrogen Generator:
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F4 . . . . .
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F3 . . . LG .
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F2 E HG HM . .
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F1 . . . . LM
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• Bring both Hydrogen-related items to the third floor, which is safe
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because the Hydrogen-compatible microchip is getting power from its
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generator:
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F4 . . . . .
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F3 E HG HM LG .
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F2 . . . . .
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F1 . . . . LM
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• Leave the Hydrogen Generator on floor three, but bring the
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Hydrogen-compatible Microchip back down with you so you can still use the
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elevator:
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F4 . . . . .
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F3 . HG . LG .
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F2 E . HM . .
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F1 . . . . LM
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• At the first floor, grab the Lithium-compatible Microchip, which is safe
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because Microchips don't affect each other:
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F4 . . . . .
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F3 . HG . LG .
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F2 . . . . .
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F1 E . HM . LM
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• Bring both Microchips up one floor, where there is nothing to fry them:
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F4 . . . . .
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F3 . HG . LG .
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F2 E . HM . LM
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F1 . . . . .
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• Bring both Microchips up again to floor three, where they can be
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temporarily connected to their corresponding generators while the elevator
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recharges, preventing either of them from being fried:
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F4 . . . . .
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F3 E HG HM LG LM
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F2 . . . . .
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F1 . . . . .
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• Bring both Microchips to the fourth floor:
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F4 E . HM . LM
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F3 . HG . LG .
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F2 . . . . .
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F1 . . . . .
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• Leave the Lithium-compatible microchip on the fourth floor, but bring
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the Hydrogen-compatible one so you can still use the elevator; this is
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safe because although the Lithium Generator is on the destination floor,
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you can connect Hydrogen-compatible microchip to the Hydrogen Generator
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there:
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F4 . . . . LM
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F3 E HG HM LG .
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F2 . . . . .
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F1 . . . . .
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• Bring both Generators up to the fourth floor, which is safe because you
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can connect the Lithium-compatible Microchip to the Lithium Generator upon
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arrival:
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F4 E HG . LG LM
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F3 . . HM . .
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F2 . . . . .
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F1 . . . . .
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• Bring the Lithium Microchip with you to the third floor so you can use
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the elevator:
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F4 . HG . LG .
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F3 E . HM . LM
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F2 . . . . .
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F1 . . . . .
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• Bring both Microchips to the fourth floor:
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F4 E HG HM LG LM
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F3 . . . . .
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F2 . . . . .
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F1 . . . . .
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In this arrangement, it takes 11 steps to collect all of the objects at the
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fourth floor for assembly. (Each elevator stop counts as one step, even if
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nothing is added to or removed from it.)
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In your situation, what is the minimum number of steps required to bring all
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of the objects to the fourth floor?
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Your puzzle answer was 31.
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--- Part Two ---
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You step into the cleanroom separating the lobby from the isolated area and
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put on the hazmat suit.
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Upon entering the isolated containment area, however, you notice some extra
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parts on the first floor that weren't listed on the record outside:
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• An elerium generator.
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• An elerium-compatible microchip.
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• A dilithium generator.
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• A dilithium-compatible microchip.
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These work just like the other generators and microchips. You'll have to get
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them up to assembly as well.
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What is the minimum number of steps required to bring all of the objects,
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including these four new ones, to the fourth floor?
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Your puzzle answer was 55.
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Both parts of this puzzle are complete! They provide two gold stars: **
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At this point, all that is left is for you to admire your advent calendar.
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If you still want to see it, you can get your puzzle input.
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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/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://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator
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. http://adventofcode.com/2016
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. http://adventofcode.com/2016/day/11/input
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