Added Binary Euler Tour

Author: MayankShah1

.idea/workspace.xml

@@ -0,0 +1,40 @@
+import euler_tour
+
+class BinaryEulerTour(euler_tour.EulerTour):
+    """ Abstract base class for performing Euler tour of a binary tree.
+
+    This version includes an additional hook invisit that is called after the tour
+    of the left subtree( if any), yet before the tour  of the right subtree( if any).
+
+    Note: Right child is always assigned index 1 in path, even if no left sibling. """
+
+    def _tour(self, p, d, path):
+        results = [None, None]
+        self._hook_previsit(p, d, path)
+        if self._tree.left(p) is not None:
+            path.append(0)
+            results[0] = self._tour(self._tree.left(p), d + 1, path)
+            path.pop()
+        self._hook_invisit(p, d, path)
+        if self._tree.right(p) is not None:
+            path.append(1)
+            results[1] = self._tour(self._tree.left(p), d + 1, path)
+            path.pop()
+        answer = self._hook_postvisit(p, d, path, results)
+        return answer
+
+    def _hook_invisit(self, p, d, path):
+        pass
+
+
+class BinaryLayout(BinaryEulerTour):
+    """Class for computing (x, y) coordinates for node of a binary tree"""
+
+    def __init__(self, tree):
+        super().__init__(tree)
+        self._count = 0
+
+    def _hook_invisit(self, p, d, path):
+        p.element().setX(self._count)
+        p.element().setY(d)
+        self._count += 1