Update erect-the-fence.py

Author: kamyu104

Python/erect-the-fence.py

@@ -14,13 +14,16 @@ def outerTrees(self, points):
         def ccw(A, B, C):
             return (B[0]-A[0])*(C[1]-A[1]) - (B[1]-A[1])*(C[0]-A[0])
 
-        if len(points) <= 3:
-            return points
         hull = []
         points.sort()
         for i in itertools.chain(xrange(len(points)), reversed(xrange(len(points)-1))):
             while len(hull) >= 2 and ccw(hull[-2], hull[-1], points[i]) < 0:
                 hull.pop()
             hull.append(points[i])
-        hull.pop()
+        if len(hull) >= 2:
+           hull.pop()
+        for i in xrange(1, (len(hull)+1)//2):
+            if hull[i] != hull[-1]:
+                break
+            hull.pop()
         return hull