feat: day 15 (70:22.00)

.aoc-cache/15.txt

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+Sensor at x=325337, y=2568863: closest beacon is at x=-518661, y=2000000
+Sensor at x=3988825, y=837820: closest beacon is at x=4305648, y=2127118
+Sensor at x=1611311, y=2053174: closest beacon is at x=2827226, y=1579510
+Sensor at x=101890, y=3940049: closest beacon is at x=955472, y=3457514
+Sensor at x=3962702, y=2558425: closest beacon is at x=4226981, y=2604726
+Sensor at x=2957890, y=2160813: closest beacon is at x=2827226, y=1579510
+Sensor at x=3907456, y=3325610: closest beacon is at x=3696221, y=3226373
+Sensor at x=3354177, y=3435919: closest beacon is at x=3696221, y=3226373
+Sensor at x=3997379, y=3071868: closest beacon is at x=3696221, y=3226373
+Sensor at x=145143, y=1714962: closest beacon is at x=-518661, y=2000000
+Sensor at x=611563, y=3148864: closest beacon is at x=955472, y=3457514
+Sensor at x=3080405, y=3904777: closest beacon is at x=3696221, y=3226373
+Sensor at x=644383, y=10732: closest beacon is at x=364635, y=-294577
+Sensor at x=3229566, y=1694167: closest beacon is at x=2827226, y=1579510
+Sensor at x=1600637, y=3984884: closest beacon is at x=955472, y=3457514
+Sensor at x=2959765, y=2820860: closest beacon is at x=2491502, y=2897876
+Sensor at x=2235330, y=3427797: closest beacon is at x=2491502, y=2897876
+Sensor at x=2428996, y=210881: closest beacon is at x=2827226, y=1579510
+Sensor at x=369661, y=687805: closest beacon is at x=364635, y=-294577
+Sensor at x=3558476, y=2123614: closest beacon is at x=4305648, y=2127118
+Sensor at x=3551529, y=2825104: closest beacon is at x=3696221, y=3226373
+Sensor at x=64895, y=3577: closest beacon is at x=364635, y=-294577
+Sensor at x=3079531, y=1538659: closest beacon is at x=2827226, y=1579510

src/bin/day_15.rs

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+use std::collections::{HashMap, HashSet};
+
+use aoc_2022::prelude::*;
+
+type Coord = (isize, isize);
+#[derive(Debug)]
+struct Reading {
+    sensor: Coord,
+    beacon: Coord,
+}
+
+type Input = Vec<Reading>;
+
+fn parse(s: &str) -> Result<Input> {
+    let mut readings = vec![];
+
+    for line in s.lines() {
+        let ints = ints(line);
+        let sensor = (
+            ints[0],
+            ints[1],
+        );
+        let beacon = (
+            ints[2],
+            ints[3],
+        );
+        readings.push(Reading { sensor, beacon });
+    }
+
+    Ok(readings)
+}
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+enum Node {
+    Sensor {
+        min_distance: isize,
+    },
+    Beacon,
+}
+
+fn manhatten(a: Coord, b: Coord) -> isize {
+    (a.0.abs_diff(b.0) + a.1.abs_diff(b.1)) as isize
+}
+
+struct Sensor {
+    coord: Coord,
+    min_distance: isize,
+}
+
+#[aoc(day = 15, parse = parse, test_cases = ["day_15.txt"])]
+fn day_15(input: Input) -> Result<()> {
+    // Part 1
+    let mut map = HashMap::<Coord, Node>::new();
+    for reading in &input {
+        let min_distance = manhatten(reading.sensor, reading.beacon);
+        map.insert(reading.sensor, Node::Sensor { min_distance });
+        map.insert(reading.beacon, Node::Beacon);
+    }
+
+    for y in -2..=22 {
+        print!("{y: >2} ");
+        for x in -2..=25 {
+            if let Some(n) = map.get(&(x, y)) {
+                let c = match n {
+                    Node::Sensor { .. } => 'S',
+                    Node::Beacon => 'B',
+                };
+                print!("{c}");
+            } else {
+                print!(".");
+            }
+        }
+        println!();
+    }
+
+    let sensors = input.iter()
+        .map(|reading| {
+            let min_distance = manhatten(reading.sensor, reading.beacon);
+            Sensor {
+                coord: reading.sensor,
+                min_distance,
+            }
+        }).collect::<Vec<_>>();
+
+    // const TARGET_Y: isize = 10;
+    const TARGET_Y: isize = 2_000_000;
+
+    let empty_cells = sensors.iter()
+        .filter(|sensor| sensor.coord.1.abs_diff(TARGET_Y) as isize <= sensor.min_distance)
+        .flat_map(|sensor| {
+            let remaining_dist = sensor.min_distance - (sensor.coord.1.abs_diff(TARGET_Y) as isize);
+            (sensor.coord.0 - remaining_dist)..=(sensor.coord.0 + remaining_dist)
+        })
+        .map(|x| (x, TARGET_Y))
+        .filter(|c| map.get(c).is_none())
+        .collect::<HashSet<_>>();
+
+    let empty_in_row = empty_cells.len();
+
+    println!("Part one: {empty_in_row}");
+
+    // Part 2
+
+    const RANGE_MIN: isize = 0;
+    // const RANGE_MAX: isize = 20;
+    const RANGE_MAX: isize = 4_000_000;
+
+    let location = sensors
+        .iter()
+        .flat_map(|sensor| {
+            let dist = sensor.min_distance + 1;
+            ((sensor.coord.0 - dist)..=(sensor.coord.1 + dist))
+                .flat_map(move |x| {
+                    let remaining_dist = dist - (sensor.coord.0.abs_diff(x) as isize);
+                    [sensor.coord.1 + remaining_dist, sensor.coord.1 - remaining_dist].into_iter()
+                        .map(move |y| (x, y))
+                })
+        })
+        .filter(|c| {
+            c.0 >= RANGE_MIN && c.0 <= RANGE_MAX
+        })
+        .filter(|c| {
+            c.1 >= RANGE_MIN && c.1 <= RANGE_MAX
+        })
+        .filter(|c| {
+            sensors.iter().all(|sensor| {
+                manhatten(*c, sensor.coord) > sensor.min_distance
+            })
+        })
+        .next().unwrap();
+
+    let tuning_frequency = location.0 * 4000000 + location.1;
+
+    println!("Part two: {tuning_frequency}");
+
+    Ok(())
+}

test_cases/day_15.txt

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+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