From 8f85eafcf28ecc77607ad2b54b4bde3bd07885bb Mon Sep 17 00:00:00 2001 From: Shivesh Mandalia Date: Wed, 21 Dec 2022 21:20:05 +0000 Subject: complete day 6 --- day06a/src/main.rs | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 85 insertions(+) create mode 100644 day06a/src/main.rs (limited to 'day06a/src') diff --git a/day06a/src/main.rs b/day06a/src/main.rs new file mode 100644 index 0000000..dc15d67 --- /dev/null +++ b/day06a/src/main.rs @@ -0,0 +1,85 @@ +/// --- Day 6: Tuning Trouble --- +/// +/// The preparations are finally complete; you and the Elves leave camp on foot and begin to make +/// your way toward the star fruit grove. +/// +/// As you move through the dense undergrowth, one of the Elves gives you a handheld device. He +/// says that it has many fancy features, but the most important one to set up right now is the +/// communication system. +/// +/// However, because he's heard you have significant experience dealing with signal-based systems, +/// he convinced the other Elves that it would be okay to give you their one malfunctioning device +/// - surely you'll have no problem fixing it. +/// +/// As if inspired by comedic timing, the device emits a few colorful sparks. +/// +/// To be able to communicate with the Elves, the device needs to lock on to their signal. The +/// signal is a series of seemingly-random characters that the device receives one at a time. +/// +/// To fix the communication system, you need to add a subroutine to the device that detects a +/// start-of-packet marker in the datastream. In the protocol being used by the Elves, the start +/// of a packet is indicated by a sequence of four characters that are all different. +/// +/// The device will send your subroutine a datastream buffer (your puzzle input); your subroutine +/// needs to identify the first position where the four most recently received characters were all +/// different. Specifically, it needs to report the number of characters from the beginning of the +/// buffer to the end of the first such four-character marker. +/// +/// For example, suppose you receive the following datastream buffer: +/// +/// ``` +/// mjqjpqmgbljsphdztnvjfqwrcgsmlb +/// ``` +/// +/// After the first three characters (mjq) have been received, there haven't been enough characters +/// received yet to find the marker. The first time a marker could occur is after the fourth +/// character is received, making the most recent four characters mjqj. Because j is repeated, this +/// isn't a marker. +/// +/// The first time a marker appears is after the seventh character arrives. Once it does, the last +/// four characters received are jpqm, which are all different. In this case, your subroutine +/// should report the value 7, because the first start-of-packet marker is complete after 7 +/// characters have been processed. +/// +/// Here are a few more examples: +/// +/// bvwbjplbgvbhsrlpgdmjqwftvncz: first marker after character 5 +/// nppdvjthqldpwncqszvftbrmjlhg: first marker after character 6 +/// nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg: first marker after character 10 +/// zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw: first marker after character 11 +/// +/// How many characters need to be processed before the first start-of-packet marker is detected? +use clap::Parser; +use itertools::Itertools; + +use std::fs::File; +use std::io::prelude::*; +use std::io::BufReader; +use std::iter::*; +use std::path::PathBuf; + +const FILEPATH: &'static str = "examples/input.txt"; +const CONS_CHARS: usize = 4; + +#[derive(Parser, Debug)] +#[clap(author, version, about, long_about = None)] +struct Cli { + #[clap(short, long, default_value = FILEPATH)] + file: PathBuf, +} + +fn main() { + let args = Cli::parse(); + + let file = File::open(&args.file).unwrap(); + let reader = BufReader::new(file); + let line = reader.lines().next().unwrap().unwrap(); + let res = line + .into_bytes() + .windows(CONS_CHARS) + .position(|b| b.iter().all_unique()) + .unwrap() + + CONS_CHARS; + + println!("{:?}", res); +} -- cgit v1.2.3