day6: complete solution

6/.gitignore

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+/target

6/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "day6"
+version = "0.1.0"
+dependencies = [
+ "itertools",
+]
+
+[[package]]
+name = "either"
+version = "1.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "60b1af1c220855b6ceac025d3f6ecdd2b7c4894bfe9cd9bda4fbb4bc7c0d4cf0"
+
+[[package]]
+name = "itertools"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "413ee7dfc52ee1a4949ceeb7dbc8a33f2d6c088194d9f922fb8318faf1f01186"
+dependencies = [
+ "either",
+]

6/Cargo.toml

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+[package]
+name = "day6"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+itertools = "0.13.0"

6/src/main.rs

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+use itertools::Itertools;
+use std::fs::File;
+use std::io::{BufRead, BufReader, Lines};
+use std::time::{Duration, Instant};
+
+// BOILERPLATE
+type InputIter = Lines<BufReader<File>>;
+
+pub fn get_input() -> InputIter {
+    let f = File::open("input").unwrap();
+    let br = BufReader::new(f);
+    br.lines()
+}
+
+fn duration_format(duration: Duration) -> String {
+    match duration.as_secs_f64() {
+        x if x > 1.0 => format!("{:.3}s", x),
+        x if x > 0.010 => format!("{:.3}ms", x * 1e3),
+        x => format!("{:.3}us", x * 1e6),
+    }
+}
+
+fn main() {
+    let input = get_input();
+    let start = Instant::now();
+    let ans1 = problem1(input);
+    let duration1 = start.elapsed();
+    println!(
+        "Problem 1 solution: {} [{}]",
+        ans1,
+        duration_format(duration1)
+    );
+
+    let input = get_input();
+    let start = Instant::now();
+    let ans2 = problem2(input);
+    let duration2 = start.elapsed();
+    println!(
+        "Problem 2 solution: {} [{}]",
+        ans2,
+        duration_format(duration2)
+    );
+    println!("Total duration: {}", duration_format(duration1 + duration2));
+}
+
+// PROBLEM 1 solution
+
+fn problem1<T: BufRead>(mut input: Lines<T>) -> u64 {
+    let s = input.next().unwrap().unwrap();
+    s.as_bytes().windows(4).enumerate().find_map(|(i, window)| {
+        if window[1..4].iter().all(|c| *c != window[0]) && window[2..4].iter().all(|c| *c != window[1]) && window[2] != window[3] {
+            println!("Unique window: {:?} at {}", window.iter().map(|c| *c as char).collect_vec(), i);
+            Some(i + 4)
+        } else {
+            None
+        }
+    }).unwrap() as u64
+}
+
+// PROBLEM 2 solution
+fn problem2<T: BufRead>(mut input: Lines<T>) -> u64 {
+    let s = input.next().unwrap().unwrap();
+    let size = 14;
+    s.as_bytes().windows(size).enumerate().find_map(|(i, window)| {
+        for i in 1..size {
+            let shifted = &window[i..];
+            if shifted.iter().enumerate().any(|(j,c)| *c == window[j]) {
+                return None
+            }
+        }
+        return Some(i + 14)
+    }).unwrap() as u64
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::*;
+    use std::io::Cursor;
+
+    const EXAMPLE1: &str = &"bvwbjplbgvbhsrlpgdmjqwftvncz";
+    const EXAMPLE2: &str = &"nppdvjthqldpwncqszvftbrmjlhg";
+    const EXAMPLE3: &str = &"nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg";
+    const EXAMPLE4: &str = &"zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw";
+
+    #[test]
+    fn problem1_example() {
+        assert_eq!(problem1(Cursor::new(EXAMPLE1).lines()), 5);
+        assert_eq!(problem1(Cursor::new(EXAMPLE2).lines()), 6);
+        assert_eq!(problem1(Cursor::new(EXAMPLE3).lines()), 10);
+        assert_eq!(problem1(Cursor::new(EXAMPLE4).lines()), 11);
+    }
+
+    #[test]
+    fn problem2_example() {
+        assert_eq!(problem2(Cursor::new(EXAMPLE1).lines()), 23);
+        assert_eq!(problem2(Cursor::new(EXAMPLE2).lines()), 23);
+        assert_eq!(problem2(Cursor::new(EXAMPLE3).lines()), 29);
+        assert_eq!(problem2(Cursor::new(EXAMPLE4).lines()), 26);
+    }
+}