chore: refactor for cargo-aoc / codspeed

src/day8.rs

@@ -0,0 +1,97 @@
+use aoc_runner_derive::{aoc, aoc_generator};
+use grid::Grid;
+use itertools::Itertools;
+use std::collections::HashSet;
+use std::io::{BufRead, Lines};
+
+#[aoc_generator(day8)]
+pub fn get_input(input: &[u8]) -> AntennaMap {
+    AntennaMap::from(input.lines())
+}
+
+pub struct AntennaMap {
+    map: Grid<u8>,
+}
+
+impl<T: BufRead> From<Lines<T>> for AntennaMap {
+    fn from(input: Lines<T>) -> Self {
+        Self { map: Grid::from(input) }
+    }
+}
+
+impl AntennaMap {
+    fn find_antinodes(&self, start: usize, reps: Option<usize>) -> Grid<bool> {
+        let mut antinodes = Grid::with_shape(self.map.width(), self.map.height(), false);
+        // find the unique frequencies in a dumb way
+        // NOTE: The dumb way is faster than the slightly-smarter ways I tried
+        let freq_set: HashSet<&u8> = HashSet::from_iter(self.map.data.iter().filter(|c| **c != b'.'));
+
+        // for each unique frequency, get all the pairs' positions
+        for freq in freq_set {
+            for pair in self
+                .map
+                .data
+                .iter()
+                .enumerate()
+                .filter(|(_, c)| *c == freq)
+                .map(|(i, _)| self.map.coord(i as i64).unwrap())
+                .permutations(2)
+            {
+                // permutations generates both pairs, ie. ((1,2),(2,1)) and ((2,1),(1,2)) so we don't need
+                // to consider the 'negative' side of the line, which will be generated by the other pair
+                let (a, b) = (pair[0], pair[1]);
+                let offset = (a.0 - b.0, a.1 - b.1);
+                for i in (start..).map_while(|i| if Some(i - start) != reps { Some(i as i64) } else { None }) {
+                    let node_pos = (a.0 + i * offset.0, a.1 + i * offset.1);
+                    if !antinodes.set(node_pos.0, node_pos.1, true) {
+                        // left the grid
+                        break;
+                    }
+                }
+            }
+        }
+        antinodes
+    }
+}
+
+// PROBLEM 1 solution
+#[aoc(day8, part1)]
+pub fn part1(map: &AntennaMap) -> u64 {
+    let antinodes = map.find_antinodes(1, Some(1));
+    antinodes.count(true) as u64
+}
+
+// PROBLEM 2 solution
+#[aoc(day8, part2)]
+pub fn part2(map: &AntennaMap) -> u64 {
+    let antinodes = map.find_antinodes(0, None);
+    antinodes.count(true) as u64
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::day8::*;
+
+    const EXAMPLE: &[u8] = b"............
+........0...
+.....0......
+.......0....
+....0.......
+......A.....
+............
+............
+........A...
+.........A..
+............
+............";
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(part1(&get_input(EXAMPLE)), 14);
+    }
+
+    #[test]
+    fn part2_example() {
+        assert_eq!(part2(&get_input(EXAMPLE)), 34);
+    }
+}