1 files changed, 17 insertions, 11 deletions

diff --git a/src/bitmap.rs b/src/bitmap.rs
index 6aa6b12..2bf8556 100644
--- a/src/bitmap.rs
+++ b/src/bitmap.rs
@@ -98,8 +98,14 @@ impl MapPoint {
     pub fn mirror_about(self, line: u32, axis: Axis) -> MapPoint {
         let MapPoint { x, y } = self;
         match axis {
-            Axis::X => MapPoint { x, y: 2 * line - y },
-            Axis::Y => MapPoint { x: 2 * line - x, y },
+            Axis::X => MapPoint {
+                x,
+                y: (2 * line).saturating_sub(y),
+            },
+            Axis::Y => MapPoint {
+                x: (2 * line).saturating_sub(x),
+                y,
+            },
         }
     }
 
@@ -259,18 +265,18 @@ where
             } else {
                 let last = queue.pop().unwrap();
                 area.insert(last);
-                for (x, y) in [(1, 0), (0, 1), (-1, 0), (0, -1)].iter() {
-                    let dir = MapPoint::try_from((last.x as i64 + x, last.y as i64 + y));
-                    if let Ok(pt) = dir {
-                        if self.contains(pt)
+                [(1, 0), (0, 1), (-1, 0), (0, -1)]
+                    .iter()
+                    .filter_map(|(x, y)| {
+                        MapPoint::try_from((last.x as i64 + x, last.y as i64 + y)).ok()
+                    })
+                    .filter(|&pt| {
+                        self.contains(pt)
                             && self.get(pt) == target
                             && self.get(pt) != replacement
                             && !area.contains(&pt)
-                        {
-                            queue.push(pt);
-                        }
-                    }
-                }
+                    })
+                    .for_each(|pt| queue.push(pt));
             }
         }
     }