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51 lines
2.6 KiB
51 lines
2.6 KiB
1 year ago
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# Day 21: Monkey Math
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[https://adventofcode.com/2022/day/21](https://adventofcode.com/2022/day/21)
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## Description
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### Part One
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The [monkeys](https://adventofcode.com/2022/day/11) are back! You're worried they're going to try to steal your stuff again, but it seems like they're just holding their ground and making various monkey noises at you.
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Eventually, one of the elephants realizes you don't speak monkey and comes over to interpret. As it turns out, they overheard you talking about trying to find the grove; they can show you a shortcut if you answer their _riddle_.
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Each monkey is given a _job_: either to _yell a specific number_ or to _yell the result of a math operation_. All of the number-yelling monkeys know their number from the start; however, the math operation monkeys need to wait for two other monkeys to yell a number, and those two other monkeys might _also_ be waiting on other monkeys.
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Your job is to _work out the number the monkey named `root` will yell_ before the monkeys figure it out themselves.
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For example:
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root: pppw + sjmn
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dbpl: 5
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cczh: sllz + lgvd
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zczc: 2
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ptdq: humn - dvpt
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dvpt: 3
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lfqf: 4
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humn: 5
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ljgn: 2
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sjmn: drzm * dbpl
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sllz: 4
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pppw: cczh / lfqf
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lgvd: ljgn * ptdq
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drzm: hmdt - zczc
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hmdt: 32
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Each line contains the name of a monkey, a colon, and then the job of that monkey:
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* A lone number means the monkey's job is simply to yell that number.
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* A job like `aaaa + bbbb` means the monkey waits for monkeys `aaaa` and `bbbb` to yell each of their numbers; the monkey then yells the sum of those two numbers.
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* `aaaa - bbbb` means the monkey yells `aaaa`'s number minus `bbbb`'s number.
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* Job `aaaa * bbbb` will yell `aaaa`'s number multiplied by `bbbb`'s number.
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* Job `aaaa / bbbb` will yell `aaaa`'s number divided by `bbbb`'s number.
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So, in the above example, monkey `drzm` has to wait for monkeys `hmdt` and `zczc` to yell their numbers. Fortunately, both `hmdt` and `zczc` have jobs that involve simply yelling a single number, so they do this immediately: `32` and `2`. Monkey `drzm` can then yell its number by finding `32` minus `2`: _`30`_.
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Then, monkey `sjmn` has one of its numbers (`30`, from monkey `drzm`), and already has its other number, `5`, from `dbpl`. This allows it to yell its own number by finding `30` multiplied by `5`: _`150`_.
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This process continues until `root` yells a number: _`152`_.
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However, your actual situation involves <span title="Advent of Code 2022: Now With Considerably More Monkeys">considerably more monkeys</span>. _What number will the monkey named `root` yell?_
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