2 files changed, 18 insertions, 23 deletions

diff --git a/aoc/datastructures.py b/aoc/datastructures.py
index c49f564..81a68e4 100644
--- a/aoc/datastructures.py
+++ b/aoc/datastructures.py
@@ -3,25 +3,28 @@ from collections import namedtuple
 
 
 class Coordinate(namedtuple("Coordinate", ["x", "y"])):
-    def __sub__(self, other: "Coordinate"):
+    def __sub__(self, other: "Coordinate") -> "Coordinate":
         return Coordinate(self.x - other.x, self.y - other.y)
 
-    def __add__(self, other: "Coordinate"):
+    def __add__(self, other: "Coordinate") -> "Coordinate":
         return Coordinate(self.x + other.x, self.y + other.y)
 
-    def manhattan_distance(self, other: "Coordinate"):
+    def manhattan_distance(self, other: "Coordinate") -> int:
         return abs(self.x - other.x) + abs(self.y - other.y)
 
     @property
-    def polarity_x(self):
+    def polarity(self) -> "Coordinate":
         try:
-            return abs(self.x) / self.x
+            px = abs(self.x) / self.x
         except ZeroDivisionError:
-            return 0
+            px = 0
 
-    @property
-    def polarity_y(self):
         try:
-            return abs(self.y) / self.y
+            py = abs(self.y) / self.y
         except ZeroDivisionError:
-            return 0
+            py = 0
+
+        return Coordinate(
+            px,
+            py,
+        )
diff --git a/day9/__init__.py b/day9/__init__.py
index a2d6d82..ba29708 100644
--- a/day9/__init__.py
+++ b/day9/__init__.py
@@ -36,26 +36,18 @@ class Assignment(BaseAssignment, ABC):
         if abs(delta.x) < 2 and abs(delta.y) < 2:
             return tail
         elif abs(delta.x) > 1 and delta.y == 0:
-            return tail + Coordinate(
-                delta.x - delta.polarity_x,
-                0,
-            )
+            return tail + delta - delta.polarity
         elif abs(delta.x) > 1 and abs(delta.y) == 1:
-            return tail + Coordinate(delta.x - delta.polarity_x, delta.y)
+            return tail + Coordinate(delta.x - delta.polarity.x, delta.y)
         elif abs(delta.y) > 1 and delta.x == 0:
-            return tail + Coordinate(
-                0,
-                delta.y - delta.polarity_y,
-            )
+            return tail + delta - delta.polarity
         elif abs(delta.y) > 1 and abs(delta.x) == 1:
             return tail + Coordinate(
                 delta.x,
-                delta.y - delta.polarity_y,
+                delta.y - delta.polarity.y,
             )
         elif abs(delta.x) > 1 and abs(delta.y) > 1:
-            return tail + Coordinate(
-                delta.x - delta.polarity_x, delta.y - delta.polarity_y
-            )
+            return tail + delta - delta.polarity
 
     def tail_positions(self, input: Iterator[str], length: int) -> Iterator[Coordinate]:
         knots = [Coordinate(0, 0) for _ in range(length)]