day8: complete solution

8/Cargo.lock

@@ -0,0 +1,30 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "day8"
+version = "0.1.0"
+dependencies = [
+ "grid",
+ "itertools",
+]
+
+[[package]]
+name = "either"
+version = "1.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "60b1af1c220855b6ceac025d3f6ecdd2b7c4894bfe9cd9bda4fbb4bc7c0d4cf0"
+
+[[package]]
+name = "grid"
+version = "0.1.0"
+
+[[package]]
+name = "itertools"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "413ee7dfc52ee1a4949ceeb7dbc8a33f2d6c088194d9f922fb8318faf1f01186"
+dependencies = [
+ "either",
+]

8/Cargo.toml

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+[package]
+name = "day8"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+grid = { version = "0.1.0", path = "../libs/grid" }
+itertools = "0.13.0"

8/src/main.rs

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+use grid::Grid;
+use itertools::Itertools;
+use std::collections::HashSet;
+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));
+}
+
+struct AntennaMap {
+    map: Grid<u8>,
+    antinodes: Grid<u8>,
+}
+
+impl<T: BufRead> From<Lines<T>> for AntennaMap {
+    fn from(input: Lines<T>) -> Self {
+        let map = Grid::from(input);
+        let width = map.width();
+        let height = map.height();
+        Self {
+            map,
+            antinodes: Grid::with_shape(width, height, b'.'),
+        }
+    }
+}
+
+// PROBLEM 1 solution
+
+fn problem1<T: BufRead>(input: Lines<T>) -> u64 {
+    let mut map = AntennaMap::from(input);
+
+    // find the unique frequencies in a dumb way
+    let freq_set: HashSet<&u8> = HashSet::from_iter(map.map.data.iter().filter(|c| **c != b'.'));
+
+    // for each unique frequency, get all the pairs' positions
+    for freq in freq_set {
+        let coords = map
+            .map
+            .data
+            .iter()
+            .enumerate()
+            .filter(|(_, c)| *c == freq)
+            .map(|(i, _)| map.map.coord(i as i64).unwrap())
+            .collect_vec();
+
+        for pair in coords.iter().permutations(2).collect_vec() {
+            let (a, b) = (pair[0], pair[1]);
+            let node_pos = (a.0 + a.0 - b.0, a.1 + a.1 - b.1);
+            map.antinodes.set(node_pos.0, node_pos.1, b'#');
+        }
+    }
+    map.antinodes.count(b'#') as u64
+}
+
+// PROBLEM 2 solution
+fn problem2<T: BufRead>(input: Lines<T>) -> u64 {
+    let mut map = AntennaMap::from(input);
+
+    // find the unique frequencies in a dumb way
+    let freq_set: HashSet<&u8> = HashSet::from_iter(map.map.data.iter().filter(|c| **c != b'.'));
+
+    // for each unique frequency, get all the pairs' positions
+    for freq in freq_set {
+        let coords = map
+            .map
+            .data
+            .iter()
+            .enumerate()
+            .filter(|(_, c)| *c == freq)
+            .map(|(i, _)| map.map.coord(i as i64).unwrap())
+            .collect_vec();
+
+        for pair in coords.iter().permutations(2).collect_vec() {
+            let (a, b) = (pair[0], pair[1]);
+            let offset = (a.0 - b.0, a.1 - b.1);
+            let mut i = 0;
+            loop {
+                let node_pos = (a.0 + i * offset.0, a.1 + i * offset.1);
+                if !map.antinodes.set(node_pos.0, node_pos.1, b'#') {
+                    break;
+                }
+                i += 1;
+            }
+        }
+    }
+    map.antinodes.count(b'#') as u64
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::*;
+    use std::io::Cursor;
+
+    const EXAMPLE: &str = &"............
+........0...
+.....0......
+.......0....
+....0.......
+......A.....
+............
+............
+........A...
+.........A..
+............
+............";
+
+    #[test]
+    fn problem1_example() {
+        let c = Cursor::new(EXAMPLE);
+        assert_eq!(problem1(c.lines()), 14);
+    }
+
+    #[test]
+    fn problem2_example() {
+        let c = Cursor::new(EXAMPLE);
+        assert_eq!(problem2(c.lines()), 34);
+    }
+}