Solve day 8

input/08-0.in

@@ -0,0 +1,12 @@
+............
+........0...
+.....0......
+.......0....
+....0.......
+......A.....
+............
+............
+........A...
+.........A..
+............
+............

input/08-1.in

@@ -0,0 +1,50 @@
+..................................3.........H.....
+..............F............................CK.....
+..................F...e...m..........C.Ki.........
+......1..................m........................
+.........F.1......................................
+.......1.....W...........3..Z............i........
+...........W...m....1.............................
+......W...........m..............N..C.............
+E............2................Z.K.......p.........
+.....Y.........4....i.........N...................
+..............W.Y....................3..9....i....
+.................................h........9.......
+.........................................Z.......H
+2...............................3.......H9........
+..2..........4T...................................
+...2..............Y...4........Z..................
+.........E.........................N...5..........
+.......................................e..........
+..............................C...................
+..E..................P.....................p.H....
+......4............................IN......h.p....
+..........................T....M.........K..p.....
+..........................G.......................
+..................................................
+...................................M..............
+.5.............G..............M...................
+.............Y..........................M.........
+.................E8...0.........................h.
+.............................P............g.......
+......5...........................................
+.............n.................................c..
+...............................g....f.......c.....
+.y..............8...t....T........................
+..7..F.............T........R..........f........u.
+.kz.......7..R....................................
+.........8..................U.........P...........
+......U.............wG....v.....P.............c...
+...0.....R..........g.............................
+.....7.....8.........g.............f..............
+....z...........G................7................
+........5........6.v.....U..f.......u........e....
+.........V....v........6......t...................
+......6..0..y.....R........V...........r..........
+...........v.......we..U.............c..r.........
+................................r.......Iu........
+k............y6..........t.................r...I..
+........k............t...........w................
+.............z....n.................I.............
+..0.................n.............................
+...............n..........V...........y........u..

src/bin/08.rs

@@ -0,0 +1,96 @@
+use std::collections::{hash_map::Entry, HashMap, HashSet};
+
+fn main() {
+    let text = std::fs::read_to_string("input/08-1.in").unwrap();
+
+    let mut antinodes = HashSet::new();
+    let mut antenna: HashMap<char, Vec<(usize, usize)>> = HashMap::new();
+
+    let mut height = 0;
+    let mut width = 0;
+
+    for (x, y, char) in text
+        .lines()
+        .enumerate()
+        .inspect(|(y, _)| height = height.max(y + 1))
+        .inspect(|(_, l)| width = l.len())
+        .flat_map(|(y, l)| {
+            l.chars()
+                .enumerate()
+                .map(move |(x, c)| (x, y, c))
+                .filter(|(_, _, c)| c != &'.')
+        })
+    {
+        match antenna.entry(char) {
+            Entry::Occupied(mut e) => {
+                for (other_x, other_y) in e.get() {
+                    if let Some((antinode_x, antinode_y)) =
+                        Option::zip((2 * x).checked_sub(*other_x), (2 * y).checked_sub(*other_y))
+                    {
+                        antinodes.insert((antinode_x, antinode_y));
+                    }
+
+                    if let Some((antinode_x, antinode_y)) =
+                        Option::zip((2 * other_x).checked_sub(x), (2 * other_y).checked_sub(y))
+                    {
+                        antinodes.insert((antinode_x, antinode_y));
+                    }
+                }
+
+                e.get_mut().push((x, y));
+            }
+            Entry::Vacant(e) => {
+                e.insert(vec![(x, y)]);
+            }
+        }
+    }
+
+    let t = antinodes
+        .iter()
+        .filter(|(x, y)| x < &width && y < &height)
+        .count();
+    println!("{}", t);
+
+    let mut antinodes = HashSet::new();
+    let mut antenna: HashMap<char, Vec<(usize, usize)>> = HashMap::new();
+
+    for (x, y, char) in text.lines().enumerate().flat_map(|(y, l)| {
+        l.chars()
+            .enumerate()
+            .map(move |(x, c)| (x, y, c))
+            .filter(|(_, _, c)| c != &'.')
+    }) {
+        match antenna.entry(char) {
+            Entry::Occupied(mut e) => {
+                for (other_x, other_y) in e.get() {
+                    let dir_x = *other_x as isize - x as isize;
+                    let dir_y = *other_y as isize - y as isize;
+                    let mut i = 1;
+                    while let Some((antinode_x, antinode_y)) = Option::zip(
+                        x.checked_add_signed(dir_x * i).filter(|&x| x < width),
+                        y.checked_add_signed(dir_y * i).filter(|&y| y < height),
+                    ) {
+                        antinodes.insert((antinode_x, antinode_y));
+                        i += 1;
+                    }
+
+                    let mut i = 0;
+                    while let Some((antinode_x, antinode_y)) = Option::zip(
+                        x.checked_add_signed(dir_x * i).filter(|&x| x < width),
+                        y.checked_add_signed(dir_y * i).filter(|&y| y < height),
+                    ) {
+                        antinodes.insert((antinode_x, antinode_y));
+                        i -= 1;
+                    }
+                }
+
+                e.get_mut().push((x, y));
+            }
+            Entry::Vacant(e) => {
+                e.insert(vec![(x, y)]);
+            }
+        }
+    }
+
+    println!("{}", antinodes.len());
+}