diff --git a/2022/src/bin/day15.rs b/2022/src/bin/day15.rs
index 004fd5a..6c622e5 100644
--- a/2022/src/bin/day15.rs
+++ b/2022/src/bin/day15.rs
@@ -1,16 +1,55 @@
-#![feature(test)]
+#![feature(test, result_option_inspect)]
 extern crate test;
+
 use aoc2022::{boilerplate, common::*};
+use itertools::Itertools;
 
 const DAY: usize = 15;
-type Parsed = Vec<usize>;
+type Parsed = Vec<((i64, i64), (i64, i64), u64)>;
 
 fn parse_input(raw: &str) -> Parsed {
-    parse_nums(raw)
+    raw.lines()
+        .map(|line| {
+            <[&str; 4]>::try_from(line[12..].replace(", y=", ",").replace(": closest beacon is at x=", ",").split(',').collect_vec())
+                .unwrap()
+                .map(|s| s.parse().unwrap())
+        })
+        .map(|[x1, y1, x2, y2]| ((x1, y1), (x2, y2)))
+        .map(|(t1, t2)| (t1, t2, manhattan(t1, t2)))
+        .collect()
 }
 
-fn part1(parsed: &Parsed, row: i64) -> usize {
-    unimplemented!()
+fn manhattan((x1, y1): (i64, i64), (x2, y2): (i64, i64)) -> u64 {
+    x1.abs_diff(x2) + y1.abs_diff(y2)
+}
+
+fn part1(parsed: &Parsed, y: i64) -> usize {
+    let max_distance = *parsed.iter().map(|(_, _, d)| d).max().unwrap();
+    let (&min_x, &max_x) = parsed.iter().map(|((x1, _), _, _)| x1).minmax().into_option().unwrap();
+
+    let mut c = 0;
+    let mut nearest = None;
+    for x in (min_x - max_distance as i64)..=(max_x + max_distance as i64) {
+        match nearest {
+            None => {
+                nearest = parsed.iter().find(|(p, _, d)| manhattan(*p, (x, y)) <= *d);
+                if nearest.is_some() {
+                    c += 1;
+                }
+            }
+            Some(&(p, _, d)) => {
+                if manhattan(p, (x, y)) <= d {
+                    c += 1;
+                } else {
+                    nearest = parsed.iter().min_by_key(|(p, _, _)| manhattan(*p, (x, y))).filter(|(p, _, d)| manhattan(*p, (x, y)) <= *d);
+                    if nearest.is_some() {
+                        c += 1;
+                    }
+                }
+            }
+        }
+    }
+    c
 }
 
 fn part2(parsed: &Parsed) -> usize {
@@ -18,12 +57,32 @@ fn part2(parsed: &Parsed) -> usize {
 }
 
 boilerplate! {
-    TEST_INPUT == "",
+    TEST_INPUT == "\
+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",
     tests: {
-        part1: { TEST_INPUT, 10 => 0 },
+        part1: { TEST_INPUT, 10 => 26 },
         part2: { TEST_INPUT => 0 },
     },
-    bench1(2_000_000) == 0,
+    unittests: {
+        manhattan: {
+            (8,7), (2,10) => 9,
+            (8,7), (-1,7) => 9_,
+        }
+    },
+    bench1(2_000_000) == 0, // 4827922 too low
     bench2 == 0,
-    bench_parse: Vec::len => 0,
+    bench_parse: Vec::len => 25,
 }