53 lines
1.4 KiB
Rust
53 lines
1.4 KiB
Rust
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use std::collections::HashSet;
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use std::fs::File;
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use std::io::{BufRead, BufReader};
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pub fn main(filename: &str) -> std::io::Result<()> {
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let file = File::open(filename)?;
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let reader = BufReader::new(file);
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let file_contents: Vec<char> = reader
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.lines()
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.map(|l| {
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l.expect("Couldn't read line")
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.chars()
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.collect::<Vec<char>>()
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})
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.flatten()
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.collect();
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let (sop_offset, start_of_packet_marker) = file_contents
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.windows(4)
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.enumerate()
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.find(|(_, w)| HashSet::<&char>::from_iter(w.iter()).len() == 4)
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.expect("Couldn't find start-of-packet marker");
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let (sow_offset, start_of_window_marker) = file_contents
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.windows(14)
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.enumerate()
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.find(|(_, w)| HashSet::<&char>::from_iter(w.iter()).len() == 14)
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.expect("Couldn't find start-of-message marker");
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println!(
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"Part 1: Start-of-packet message is ‘{}’ at offset {}",
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start_of_packet_marker
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.into_iter()
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.map(|c| c.to_string())
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.collect::<Vec<String>>()
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.join(""),
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sop_offset + 4
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);
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println!(
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"Part 2: Start-of-packet message is ‘{}’ at offset {}",
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start_of_window_marker
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.into_iter()
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.map(|c| c.to_string())
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.collect::<Vec<String>>()
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.join(""),
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sow_offset + 14
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);
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Ok(())
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}
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