Day 15, puzzle 2

src/bin/d15p2.rs

@@ -0,0 +1,33 @@
+use aoc22::{day15, util};
+use itertools::Itertools;
+
+const COORD_MAX: isize = 4000000;
+
+pub fn main() {
+    let sensors = day15::parse_sensors(&util::parse_input());
+
+    for row in 0..=COORD_MAX {
+        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;
+        for range in covered {
+            let (min, max) = range.into_inner();
+            if min == max_x + 2 {
+                let x = max_x + 1;
+                println!(
+                    "x = {}, y = {}, tuning freq = {}",
+                    x,
+                    row,
+                    x * 4000000 + row
+                )
+            } else if max_x != isize::MIN && min > max_x + 2 {
+                panic!("More than one coordinate free: {}..{}", max_x + 1, min - 1);
+            }
+            max_x = max_x.max(max);
+        }
+    }
+}