diff --git a/src/day10/main.rs b/src/day10/main.rs
index 23f70db..1ca696e 100644
--- a/src/day10/main.rs
+++ b/src/day10/main.rs
@@ -1,3 +1,4 @@
+use std::cmp::Ordering;
 use std::collections::{HashMap, HashSet};
 use std::fs::File;
 use std::io::{BufRead, BufReader};
@@ -45,6 +46,18 @@ impl Sub for &XY {
     }
 }
 
+impl PartialOrd for XY {
+    fn partial_cmp(&self, other: &XY) -> Option<Ordering> {
+        self.angle().partial_cmp(&other.angle())
+    }
+}
+
+impl Ord for XY {
+    fn cmp(&self, other: &XY) -> Ordering {
+        self.angle().partial_cmp(&other.angle()).unwrap()
+    }
+}
+
 impl XY {
     fn direction(&self) -> Self {
         let d = gcd(self.y, self.x).abs();
@@ -57,13 +70,57 @@ impl XY {
             self.clone()
         }
     }
+
+    fn angle(&self) -> f64 {
+        (self.y as f64).atan2(self.x as f64) * (180 as f64 / std::f64::consts::PI)
+    }
 }
 
 struct MonitoringStation {
     map: HashMap<XY, Position>,
+    size_x: usize,
+    size_y: usize,
 }
 
 impl MonitoringStation {
+    fn laser(&self, root: &XY) -> impl Iterator<Item = XY> + '_ {
+        let mut map: HashMap<XY, Vec<XY>> = HashMap::new();
+        map = self
+            .map
+            .iter()
+            .filter_map(|(xy, pos)| {
+                if *pos == Position::Empty {
+                    return None;
+                }
+                let rel = xy - &root;
+                Some((xy, rel.direction()))
+            })
+            .fold(map, |mut acc, (xy, dir)| {
+                acc.entry(dir).or_insert(vec![]).push(xy.clone());
+                acc
+            });
+        let mut angles = map.keys().cloned().collect::<Vec<XY>>();
+        angles.sort();
+
+        let mut popped = true;
+        let mut cycles = 0;
+        while popped {
+            popped = false;
+            cycles += 1;
+            angles.iter().for_each(|xy| match map.get_mut(xy) {
+                Some(xy) => {
+                    if let Some(xy) = xy.pop() {
+                        popped = true;
+                        println!("{:?}", xy)
+                    }
+                }
+                None => (),
+            });
+        }
+        println!("cycles: {}", cycles);
+        self.map.iter().map(|(xy, _)| xy.clone())
+    }
+
     fn find(&self) -> (usize, XY) {
         let best = (0, XY::from((0, 0)));
         self.map
@@ -105,10 +162,12 @@ where
 {
     fn from(reader: T) -> Self {
         let map: HashMap<XY, Position> = HashMap::new();
+        let mut size_y = 0;
         let map = reader
             .split(b'\n')
             .enumerate()
             .flat_map(|(y, line)| {
+                size_y += 1;
                 line.unwrap()
                     .iter()
                     .enumerate()
@@ -123,15 +182,23 @@ where
                 map.insert(xy.clone(), p.clone());
                 map
             });
-        MonitoringStation { map }
+        let size_x = map.iter().count() / size_y;
+        MonitoringStation {
+            map,
+            size_x,
+            size_y,
+        }
     }
 }
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     let f = File::open("input10")?;
     let reader = BufReader::new(f);
-    let best = MonitoringStation::from(reader).find();
+    let station = MonitoringStation::from(reader);
+    let best = station.find();
+    let test = station.laser(&best.1).next();
     println!("best: {:?}", best);
+    println!("test: {:?}", test);
     Ok(())
 }