Day 8 done

2024/rust/src/day8.rs

@@ -0,0 +1,115 @@
+mod prelude;
+pub use crate::prelude::*;
+
+fn main() {
+    let input = day_input(8);
+    show_answers(part1(&input), part2(&input));
+}
+
+fn part1(input: &str) -> usize {
+    let mut map: HashMap<u8, HashSet<(i64, i64)>> = HashMap::new();
+    let mut antinodes: HashSet<(i64, i64)> = HashSet::new();
+    let (width, height) = (
+        input.lines().count() as i64,
+        input.lines().next().unwrap().len() as i64,
+    );
+    for (y, line) in input.lines().enumerate() {
+        for (x, c) in line.bytes().enumerate() {
+            if c == b'.' {
+                continue;
+            }
+            map.entry(c)
+                .or_insert_with(|| HashSet::new())
+                .insert((x as i64, y as i64));
+        }
+    }
+    for nodes in map.values() {
+        println!("{nodes:?}");
+        for (i, (x1, y1)) in nodes.iter().enumerate() {
+            for (j, (x2, y2)) in nodes.iter().enumerate() {
+                if i == j {
+                    continue;
+                }
+                let (dx, dy) = (x1 - x2, y1 - y2);
+                let (a1x, a1y) = (x1 + dx, y1 + dy);
+                let (a2x, a2y) = (x2 - dx, y2 - dy);
+                if a1x >= 0 && a1x < width && a1y >= 0 && a1y < height {
+                    antinodes.insert((a1x, a1y));
+                }
+                if a2x >= 0 && a2x < width && a2y >= 0 && a2y < height {
+                    antinodes.insert((a2x, a2y));
+                }
+            }
+        }
+    }
+    antinodes.len()
+}
+
+fn part2(input: &str) -> usize {
+    let mut map: HashMap<u8, HashSet<(i64, i64)>> = HashMap::new();
+    let mut antinodes: HashSet<(i64, i64)> = HashSet::new();
+    let (width, height) = (
+        input.trim().lines().count() as i64,
+        input.lines().next().unwrap().trim().len() as i64,
+    );
+    for (y, line) in input.lines().enumerate() {
+        for (x, c) in line.bytes().enumerate() {
+            if c == b'.' {
+                continue;
+            }
+            map.entry(c)
+                .or_insert_with(|| HashSet::new())
+                .insert((x as i64, y as i64));
+        }
+    }
+    for nodes in map.values() {
+        for (i, (x1, y1)) in nodes.iter().enumerate() {
+            for (j, (x2, y2)) in nodes.iter().enumerate() {
+                antinodes.insert((*x1, *y1));
+                antinodes.insert((*x2, *y2));
+                if i == j {
+                    continue;
+                }
+                let (dx, dy) = (x1 - x2, y1 - y2);
+                let (mut a1x, mut a1y) = (x1 + dx, y1 + dy);
+                while a1x >= 0 && a1x < width && a1y >= 0 && a1y < height {
+                    antinodes.insert((a1x, a1y));
+                    println!("{a1x} {a1y} {}", antinodes.len());
+                    a1x += dx;
+                    a1y += dy;
+                }
+                let (mut a2x, mut a2y) = (x2 - dx, y2 - dy);
+                while a2x >= 0 && a2x < width && a2y >= 0 && a2y < height {
+                    antinodes.insert((a2x, a2y));
+                    println!("{a2x} {a2y} {}", antinodes.len());
+                    a2x -= dx;
+                    a2y -= dy;
+                }
+            }
+        }
+    }
+    antinodes.len()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test() {
+        let input = "............
+........0...
+.....0......
+.......0....
+....0.......
+......A.....
+............
+............
+........A...
+.........A..
+............
+............";
+        assert_eq!(part1(input), 14);
+        assert_eq!(part2(input), 34);
+    }
+}