113 lines
4.6 KiB
Plaintext
113 lines
4.6 KiB
Plaintext
Advent of Code
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br0xen (AoC++) 12*
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{ʼyearʼ:2022}
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--- Day 6: Tuning Trouble ---
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The preparations are finally complete; you and the Elves leave camp on
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foot and begin to make your way toward the star fruit grove.
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As you move through the dense undergrowth, one of the Elves gives you a
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handheld device. He says that it has many fancy features, but the most
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important one to set up right now is the communication system.
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However, because he's heard you have significant experience dealing with
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signal-based systems, he convinced the other Elves that it would be okay
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to give you their one malfunctioning device - surely you'll have no
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problem fixing it.
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As if inspired by comedic timing, the device emits a few colorful sparks.
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To be able to communicate with the Elves, the device needs to lock on to
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their signal. The signal is a series of seemingly-random characters that
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the device receives one at a time.
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To fix the communication system, you need to add a subroutine to the
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device that detects a start-of-packet marker in the datastream. In the
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protocol being used by the Elves, the start of a packet is indicated by a
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sequence of four characters that are all different.
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The device will send your subroutine a datastream buffer (your puzzle
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input); your subroutine needs to identify the first position where the
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four most recently received characters were all different. Specifically,
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it needs to report the number of characters from the beginning of the
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buffer to the end of the first such four-character marker.
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For example, suppose you receive the following datastream buffer:
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mjqjpqmgbljsphdztnvjfqwrcgsmlb
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After the first three characters (mjq) have been received, there haven't
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been enough characters received yet to find the marker. The first time a
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marker could occur is after the fourth character is received, making the
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most recent four characters mjqj. Because j is repeated, this isn't a
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marker.
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The first time a marker appears is after the seventh character arrives.
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Once it does, the last four characters received are jpqm, which are all
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different. In this case, your subroutine should report the value 7,
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because the first start-of-packet marker is complete after 7 characters
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have been processed.
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Here are a few more examples:
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• bvwbjplbgvbhsrlpgdmjqwftvncz: first marker after character 5
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• nppdvjthqldpwncqszvftbrmjlhg: first marker after character 6
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• nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg: first marker after character 10
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• zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw: first marker after character 11
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How many characters need to be processed before the first start-of-packet
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marker is detected?
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Your puzzle answer was 1544.
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--- Part Two ---
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Your device's communication system is correctly detecting packets, but
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still isn't working. It looks like it also needs to look for messages.
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A start-of-message marker is just like a start-of-packet marker, except it
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consists of 14 distinct characters rather than 4.
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Here are the first positions of start-of-message markers for all of the
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above examples:
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• mjqjpqmgbljsphdztnvjfqwrcgsmlb: first marker after character 19
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• bvwbjplbgvbhsrlpgdmjqwftvncz: first marker after character 23
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• nppdvjthqldpwncqszvftbrmjlhg: first marker after character 23
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• nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg: first marker after character 29
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• zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw: first marker after character 26
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How many characters need to be processed before the first start-of-message
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marker is detected?
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Your puzzle answer was 2145.
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Both parts of this puzzle are complete! They provide two gold stars: **
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References
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Visible links
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. https://adventofcode.com/
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. https://adventofcode.com/2022/about
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. https://adventofcode.com/2022/events
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. https://adventofcode.com/2022/settings
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. https://adventofcode.com/2022/auth/logout
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. Advent of Code Supporter
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https://adventofcode.com/2022/support
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. https://adventofcode.com/2022
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. https://adventofcode.com/2022
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. https://adventofcode.com/2022/support
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. https://adventofcode.com/2022/sponsors
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. https://adventofcode.com/2022/leaderboard
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. https://adventofcode.com/2022/stats
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. https://adventofcode.com/2022/sponsors
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. https://adventofcode.com/2016/day/6
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. https://adventofcode.com/2016/day/25
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. https://adventofcode.com/2019/day/7
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. https://adventofcode.com/2019/day/9
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. https://adventofcode.com/2019/day/16
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. https://adventofcode.com/2021/day/25
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. https://adventofcode.com/2022
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. https://adventofcode.com/2022/day/6/input
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