AVL_Tree implement in python

Trees/AVLTree.py

@@ -0,0 +1,175 @@
+class Node(object):
+    def __init__(self, data, left = None, right = None):
+        self.data = data
+        self.left = left
+        self.right = right
+        self.BF = 0             #Balance Factor
+
+
+class AVL_Tree(object):
+    def __init__(self):
+        self.root = None
+
+    def insert(self, data):
+        pNew = Node(data)
+
+        if self.root == None:
+            self.root = pNew
+            return True
+
+        a = self.root
+        pa = None
+        Cur = self.root
+        pCur = None
+        subroot = None
+
+        while Cur != None:
+            if Cur.data == data:
+                return False
+            if Cur.BF != 0:
+                a = Cur
+                pa = pCur
+            if data < Cur.data:
+                pCur = Cur
+                Cur = Cur.left
+            elif data > Cur.data:
+                pCur = Cur;
+                Cur = Cur.right
+
+        if data < pCur.data:
+            pCur.left = pNew
+        else:
+            pCur.right = pNew
+
+        balance = None
+        Ca = None
+        CCa = None
+
+        if data < a.data:
+            Cur = a.left
+            Ca = Cur
+            balance = 1
+        else:
+            Cur = a.right
+            Ca = Cur
+            balance = -1
+
+        while Cur != pNew:
+            if data < Cur.data:
+                Cur.BF = 1
+                Cur = Cur.left
+            else:
+                Cur.BF = -1
+                Cur = Cur.right
+
+        if a.BF == 0 or ((a.BF + balance) == 0):
+            a.BF = a.BF + balance
+            return True
+
+        if balance == 1:
+            if Ca.BF == 1:
+                a.left = Ca.right
+                Ca.right = a
+                a.BF = 0
+                Ca.BF = 0
+                subroot = Ca
+            else:
+                CCa = Ca.right
+                Ca.right = CCa.left
+                a.left = CCa.right
+                CCa.left = Ca
+                CCa.right = a
+
+                if CCa.BF == 0:
+                    a.BF = 0
+                    Ca.BF = 0
+                elif CCa.BF == 1:
+                    a.BF = -1
+                    Ca.BF = 0
+                elif CCa.BF == -1:
+                    a.BF = 0
+                    Ca.BF = 1
+
+                CCa.BF = 0
+                subroot = CCa
+        else:
+            if Ca.BF == -1:
+                a.right = Ca.left
+                Ca.left = a
+                a.BF = 0
+                Ca.BF = 0
+                subroot = Ca
+            else:
+                CCa = Ca.left
+                Ca.left = CCa.right
+                a.right = CCa.left
+                CCa.right = Ca
+                CCa.left = a
+
+                if CCa.BF == 0:
+                    a.BF = 0
+                    Ca.BF = 0
+                elif CCa.BF == 1:
+                    a.BF = 0
+                    Ca.BF = -1
+                elif CCa.BF == -1:
+                    a.BF = 1
+                    Ca.BF = 0
+                CCa.BF = 0
+                subroot = CCa
+
+        if pa == None:
+            self.root = subroot
+        elif a == pa.left:
+            pa.left = subroot
+        else:
+            pa.right = subroot
+
+        return True
+
+    def in_order(self):
+        def _in_order(root):
+            if root:
+                _in_order(root.left)
+                print(root.data)
+                _in_order(root.right)
+        _in_order(self.root)
+
+    def pre_order(self):
+        def _pre_order(root):
+            if root:
+                print(root.data)
+                _pre_order(root.left)
+                _pre_order(root.right)
+        _pre_order(self.root)
+
+    def post_order(self):
+        def _post_order(root):
+            if root:
+                _post_order(root.left)
+                _post_order(root.right)
+                print(root.data)
+        _post_order(self.root)
+
+if __name__ == '__main__':
+    avl_tree = AVL_Tree()
+    avl_tree.insert(40)
+    avl_tree.insert(4)
+    avl_tree.insert(34)
+    avl_tree.insert(45)
+    avl_tree.insert(14)
+    avl_tree.insert(55)
+    avl_tree.insert(48)
+    avl_tree.insert(13)
+    avl_tree.insert(15)
+    avl_tree.insert(49)
+    avl_tree.insert(47)
+
+    print("pre order")
+    avl_tree.pre_order()
+    print()
+    print("in order")
+    avl_tree.in_order()
+    print()
+    print("post order")
+    avl_tree.post_order()