Day 10 part1 + WIP of part 2

diff --git a/src/day10.rs b/src/day10.rs
new file mode 100644 (file)
index 0000000..9b8aebb
--- /dev/null
+++ b/src/day10.rs
@@ -0,0 +1,224 @@
+use std::collections::{HashMap, HashSet};
+
+pub fn read_map(raw: &str) -> Vec<(i32, i32)> {
+    let lines: Vec<&str> = raw.lines().map(|l| l.trim()).collect();
+    let mut map = Vec::<(i32, i32)>::new();
+    for x in 0 .. lines[0].len() {
+        for y in 0 .. lines.len() {
+            if lines[y].chars().nth(x) == Some('#') {
+                map.push((x as i32, y as i32));
+            }
+        }
+    }
+    map
+}
+
+fn angle(x1: i32, y1: i32, x2: i32, y2: i32) -> i64 {
+    // Axis are reverted to match the clockwise laser rotation beginning up.
+    let angle_f64 = (2.0 * std::f64::consts::PI - ((x1 - x2) as f64).atan2((y1 - y2) as f64)) % (2.0 * std::f64::consts::PI);
+    (angle_f64 * 1_000_000.0) as i64
+}
+
+fn squared_distance(x1: i32, y1: i32, x2: i32, y2: i32) -> i64 {
+    ((x1 - x2) as i64).pow(2) + ((y1 - y2) as i64).pow(2)
+}
+
+pub fn find_best_location(map: &[(i32, i32)]) -> (usize, (i32, i32)) {
+    let mut best_nb_observable_asteroid = 0;
+    let (mut best_x, mut best_y) = (0, 0);
+    for (x1, y1) in map {
+        let mut angles = HashSet::<i64>::new();
+        for (x2, y2) in map {
+            angles.insert(angle(*x1, *y1, *x2, *y2));
+        }
+        let n = angles.len();
+        if n > best_nb_observable_asteroid {
+            best_nb_observable_asteroid = n;
+            best_x = *x1;
+            best_y = *y1;
+        }
+    }
+    (best_nb_observable_asteroid, (best_x, best_y))
+}
+
+pub fn location_nth_vaporized_asteroid(pos: (i32, i32), map: &[(i32, i32)], n: usize) -> (i32, i32) {
+    // Angle -> []
+    let mut asteroids = HashMap::<i64, Vec<((i32, i32), i64)>>::new();
+
+    let (x1, y1) = pos;
+    for (x2, y2) in map {
+        let angle = angle(x1, y1, *x2 , *y2);
+        let dist = squared_distance(x1, y1, *x2 , *y2);
+        match asteroids.get_mut(&angle) {
+            Some (lineup_asteroids) => lineup_asteroids.push(((*x2, *y2), dist)),
+            None => { asteroids.insert(angle, vec![((*x2, *y2), dist)]); }
+        }
+    }
+
+    let mut sorted_angles: Vec<i64> = asteroids.keys().copied().collect();
+    sorted_angles.sort();
+
+    asteroids.values_mut().for_each(|lineup_asteroids| lineup_asteroids.sort_by(|(_, l1), (_, l2)| l1.cmp(l2)));
+
+    dbg!(&sorted_angles);
+    dbg!(&asteroids);
+    //return (0, 0);
+
+    let mut i = 1;
+    loop {
+        for angle in &sorted_angles {
+            if let Some (lineup_asteroids) = asteroids.get_mut(angle) {
+                let ((x, y), _) = lineup_asteroids.remove(0);
+                if i == n {
+                    return (x, y)
+                } else if lineup_asteroids.is_empty() {
+                    asteroids.remove(angle);
+                }
+                i += 1;
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn part1_sample_1() {
+        let raw_map =
+            ".#..#
+             .....
+             #####
+             ....#
+             ...##";
+        let map = read_map(raw_map);
+        assert_eq!(find_best_location(&map).0, 8);
+    }
+
+    #[test]
+    fn part1_sample_2() {
+        let raw_map =
+            "......#.#.
+             #..#.#....
+             ..#######.
+             .#.#.###..
+             .#..#.....
+             ..#....#.#
+             #..#....#.
+             .##.#..###
+             ##...#..#.
+             .#....####";
+        let map = read_map(raw_map);
+        assert_eq!(find_best_location(&map).0, 33);
+    }
+
+    #[test]
+    fn part1_sampl3() {
+        let raw_map =
+            "#.#...#.#.
+             .###....#.
+             .#....#...
+             ##.#.#.#.#
+             ....#.#.#.
+             .##..###.#
+             ..#...##..
+             ..##....##
+             ......#...
+             .####.###.";
+        let map = read_map(raw_map);
+        assert_eq!(find_best_location(&map).0, 35);
+    }
+
+    #[test]
+    fn part1_sample_4() {
+        let raw_map =
+            ".#..#..###
+             ####.###.#
+             ....###.#.
+             ..###.##.#
+             ##.##.#.#.
+             ....###..#
+             ..#.#..#.#
+             #..#.#.###
+             .##...##.#
+             .....#.#..";
+        let map = read_map(raw_map);
+        assert_eq!(find_best_location(&map).0, 41);
+    }
+
+    #[test]
+    fn part1_sample_5() {
+        let raw_map =
+            ".#..##.###...#######
+             ##.############..##.
+             .#.######.########.#
+             .###.#######.####.#.
+             #####.##.#.##.###.##
+             ..#####..#.#########
+             ####################
+             #.####....###.#.#.##
+             ##.#################
+             #####.##.###..####..
+             ..######..##.#######
+             ####.##.####...##..#
+             .#####..#.######.###
+             ##...#.##########...
+             #.##########.#######
+             .####.#.###.###.#.##
+             ....##.##.###..#####
+             .#.#.###########.###
+             #.#.#.#####.####.###
+             ###.##.####.##.#..##";
+        let map = read_map(raw_map);
+        assert_eq!(find_best_location(&map).0, 210);
+    }
+
+
+    #[test]
+    fn part2_sample_1() {
+        let raw_map =
+            ".#....#####...#..
+             ##...##.#####..##
+             ##...#...#.#####.
+             ..#.....X...###..
+             ..#.#.....#....##";
+        let map = read_map(raw_map);
+        let pos = (8, 3);
+        let pos_200th = location_nth_vaporized_asteroid(pos, &map, 200);
+        dbg!(pos_200th);
+        assert_eq!(2, 210);
+    }
+    /*
+
+    #[test]
+    fn part2_sample_2() {
+        let raw_map =
+            ".#..##.###...#######
+             ##.############..##.
+             .#.######.########.#
+             .###.#######.####.#.
+             #####.##.#.##.###.##
+             ..#####..#.#########
+             ####################
+             #.####....###.#.#.##
+             ##.#################
+             #####.##.###..####..
+             ..######..##.#######
+             ####.##.####...##..#
+             .#####..#.######.###
+             ##...#.##########...
+             #.##########.#######
+             .####.#.###.###.#.##
+             ....##.##.###..#####
+             .#.#.###########.###
+             #.#.#.#####.####.###
+             ###.##.####.##.#..##";
+        let map = read_map(raw_map);
+        let pos = find_best_location(&map).1;
+        let pos_200th = location_nth_vaporized_asteroid(pos, &map, 200);
+        dbg!(pos_200th);
+        assert_eq!(2, 210);
+    }
+    */
+}
\ No newline at end of file

diff --git a/src/main.rs b/src/main.rs
index 99ea6e0..c025b79 100644 (file)
--- a/src/main.rs
+++ b/src/main.rs
@@ -10,6 +10,7 @@ mod day03;
 mod day06;
 mod day07;
 mod day08;
+mod day10;
 mod day11;
 
 fn day01() -> String {
@@ -71,7 +72,8 @@ fn day09() -> String {
 }
 
 fn day10() -> String {
-    format!("")
+    let map = day10::read_map(&fs::read_to_string("data/day10.input").unwrap());
+    format!("part1: {}, part2: {}", day10::find_best_location(&map).0, "")
 }
 
 fn day11() -> String {