Day 15, puzzle 1

src/bin/d15p1.rs

@@ -0,0 +1,39 @@
+use aoc22::{day15, util};
+use itertools::Itertools;
+
+const ROW: isize = 2000000;
+
+pub fn main() {
+    let sensors = day15::parse_sensors(&util::parse_input());
+
+    let covered = sensors
+        .iter()
+        .map(|s| s.covered(ROW))
+        .filter(|r| !r.is_empty())
+        .sorted_by_key(|r| *r.start());
+
+    let mut max_x = isize::MIN;
+    let mut total_covered = 0;
+    for range in covered {
+        let (min, max) = range.into_inner();
+        if min > max_x {
+            total_covered += max - min + 1;
+        } else if max > max_x {
+            total_covered += max - max_x;
+        }
+        max_x = max_x.max(max);
+    }
+
+    let n_beacons = sensors
+        .iter()
+        .map(|s| s.loc_b)
+        .filter(|b| b.0 == ROW)
+        .unique()
+        .count() as isize;
+
+    println!(
+        "Impossible positions in row {}: {}",
+        ROW,
+        total_covered - n_beacons
+    );
+}