Add day 15

Cargo.toml

@@ -65,4 +65,8 @@ path = "src/day13/main.rs"
 name = "day14"
 path = "src/day14/main.rs"
 
+[[bin]]
+name = "day15"
+path = "src/day15/main.rs"
+
 [dependencies]

day15.txt

@@ -0,0 +1,26 @@
+Sensor at x=3772068, y=2853720: closest beacon is at x=4068389, y=2345925
+Sensor at x=78607, y=2544104: closest beacon is at x=-152196, y=4183739
+Sensor at x=3239531, y=3939220: closest beacon is at x=3568548, y=4206192
+Sensor at x=339124, y=989831: closest beacon is at x=570292, y=1048239
+Sensor at x=3957534, y=2132743: closest beacon is at x=3897332, y=2000000
+Sensor at x=1882965, y=3426126: closest beacon is at x=2580484, y=3654136
+Sensor at x=1159443, y=3861139: closest beacon is at x=2580484, y=3654136
+Sensor at x=2433461, y=287013: closest beacon is at x=2088099, y=-190228
+Sensor at x=3004122, y=3483833: closest beacon is at x=2580484, y=3654136
+Sensor at x=3571821, y=799602: closest beacon is at x=3897332, y=2000000
+Sensor at x=2376562, y=1539540: closest beacon is at x=2700909, y=2519581
+Sensor at x=785113, y=1273008: closest beacon is at x=570292, y=1048239
+Sensor at x=1990787, y=38164: closest beacon is at x=2088099, y=-190228
+Sensor at x=3993778, y=3482849: closest beacon is at x=4247709, y=3561264
+Sensor at x=3821391, y=3986080: closest beacon is at x=3568548, y=4206192
+Sensor at x=2703294, y=3999015: closest beacon is at x=2580484, y=3654136
+Sensor at x=1448314, y=2210094: closest beacon is at x=2700909, y=2519581
+Sensor at x=3351224, y=2364892: closest beacon is at x=4068389, y=2345925
+Sensor at x=196419, y=3491556: closest beacon is at x=-152196, y=4183739
+Sensor at x=175004, y=138614: closest beacon is at x=570292, y=1048239
+Sensor at x=1618460, y=806488: closest beacon is at x=570292, y=1048239
+Sensor at x=3974730, y=1940193: closest beacon is at x=3897332, y=2000000
+Sensor at x=2995314, y=2961775: closest beacon is at x=2700909, y=2519581
+Sensor at x=105378, y=1513086: closest beacon is at x=570292, y=1048239
+Sensor at x=3576958, y=3665667: closest beacon is at x=3568548, y=4206192
+Sensor at x=2712265, y=2155055: closest beacon is at x=2700909, y=2519581

day15_test.txt

@@ -0,0 +1,14 @@
+Sensor at x=2, y=18: closest beacon is at x=-2, y=15
+Sensor at x=9, y=16: closest beacon is at x=10, y=16
+Sensor at x=13, y=2: closest beacon is at x=15, y=3
+Sensor at x=12, y=14: closest beacon is at x=10, y=16
+Sensor at x=10, y=20: closest beacon is at x=10, y=16
+Sensor at x=14, y=17: closest beacon is at x=10, y=16
+Sensor at x=8, y=7: closest beacon is at x=2, y=10
+Sensor at x=2, y=0: closest beacon is at x=2, y=10
+Sensor at x=0, y=11: closest beacon is at x=2, y=10
+Sensor at x=20, y=14: closest beacon is at x=25, y=17
+Sensor at x=17, y=20: closest beacon is at x=21, y=22
+Sensor at x=16, y=7: closest beacon is at x=15, y=3
+Sensor at x=14, y=3: closest beacon is at x=15, y=3
+Sensor at x=20, y=1: closest beacon is at x=15, y=3

src/day15/main.rs

@@ -0,0 +1,145 @@
+use std::cmp::max;
+use std::collections::HashSet;
+use base::read_file;
+
+#[derive(Debug, Copy, Clone, Hash, Eq, PartialEq)]
+struct Pos(i32, i32);
+
+#[derive(Debug, Clone)]
+struct Beacon {
+    pos: Pos,
+    beacon: Pos,
+}
+
+#[derive(Copy, Clone, Debug)]
+struct Range {
+    start: i32,
+    end: i32,
+}
+
+impl Range {
+    fn new(start: i32, end: i32) -> Self {
+        Range { start, end }
+    }
+
+    fn contains(&self, number: i32) -> bool {
+        number >= self.start && number <= self.end
+    }
+
+    fn fully_overlap(&self, other: &Range) -> bool {
+        self.contains(other.start) && self.contains(other.end)
+    }
+
+    fn partly_overlap(&self, other: &Range) -> bool {
+        self.contains(other.start) || self.contains(other.end)
+    }
+}
+
+struct YLine {
+    y: i32,
+    start_x: i32,
+    start_y: i32,
+}
+
+impl Beacon {
+    fn possible_positions_into_of(&self, positions: &mut HashSet<Pos>, y: i32) {
+        let distance = self.get_distance();
+        for x in -distance..=distance {
+            if x.abs() + (self.pos.1 - y).abs() <= distance {
+                positions.insert(Pos(self.pos.0 + x, y));
+            }
+        }
+    }
+
+    fn get_distance(&self) -> i32 {
+        let Pos(px, py) = self.pos;
+        let Pos(bx, by) = self.beacon;
+        (px - bx).abs() + (py - by).abs()
+    }
+}
+
+fn main() {
+    let lines = read_file("day15.txt");
+    let mut beacons = vec![];
+
+    for line in lines {
+        beacons.push(
+            line.split([' ', '=', ':', ','])
+                .filter_map(|tok| tok.parse::<i32>().ok())
+                .collect::<Vec<_>>()
+                .chunks_exact(4)
+                .map(|positions| Beacon { pos: Pos(positions[0], positions[1]), beacon: Pos(positions[2], positions[3]) })
+                .next()
+                .unwrap()
+        );
+    }
+
+    let mut possible_positions = HashSet::new();
+
+    println!("Found {} beacons", beacons.len());
+
+    println!("Inserting possible positions");
+    let y = 2000000;
+
+    for (idx, beacon) in beacons.iter().enumerate() {
+        println!("Generating positions for beacon {}", idx);
+        beacon.possible_positions_into_of(&mut possible_positions, y);
+    }
+
+    println!("Inserting beacons");
+
+    for beacon in &beacons {
+        possible_positions.remove(&beacon.pos);
+        possible_positions.remove(&beacon.beacon);
+    }
+
+
+    println!("Searching for possible positions");
+
+    let count = possible_positions.iter().filter(|pos| pos.1 == y).count();
+
+    println!("Found {} at {}", count, y);
+
+    let max = 4000001;
+    for y in 0..max {
+        if y % 1000 == 0 {
+            println!("Y is {}/{}", y, max);
+        }
+        let mut beacon_radiation = vec![];
+        for beacon in &beacons {
+            let distance = (beacon.pos.1 - y as i32).abs();
+            let max_distance = beacon.get_distance();
+            if distance <= max_distance {
+                let start_x = beacon.pos.0 - (max_distance - distance);
+                let end_x = beacon.pos.0 + (max_distance - distance);
+                beacon_radiation.push(Range::new(start_x, end_x));
+            }
+        }
+
+        beacon_radiation.sort_by(|r1, r2| r1.start.cmp(&r2.start));
+
+        let mut start: Option<Range> = None;
+        for range in beacon_radiation {
+            match start {
+                None => {
+                    start = Some(range);
+                }
+                Some(before) => {
+                    if range.partly_overlap(&before) || (range.start - before.end) == 1 {
+                        if range.end > before.end {
+                            start = Some(Range::new(before.start, range.end));
+                        }
+                    }
+                }
+            }
+        }
+
+        if let Some(sol) = start {
+            if sol.end < max {
+                let x = sol.end + 1;
+                println!("Possible solution: {}/{} Distress: {}", x, y, (x as i64) * 4000000 + (y as i64));
+                break;
+            }
+        }
+    }
+}