Binary Search Tree implementation in Python

Author: OmkarPathak

Programs/P43_BinarySearchTree.py

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+# Author: OMKAR PATHAK
+# This program illustrates an example of Binary Search Tree using Python
+
+class Node(object):
+    def __init__(self, data):
+        self.data = data
+        self.leftChild = None
+        self.rightChild = None
+
+    def insert(self, data):
+        ''' For inserting the data in the Tree '''
+        if self.data == data:
+            return False        # As BST cannot contain duplicate data
+
+        elif data < self.data:
+            ''' Data less than the root data is placed to the left of the root '''
+            if self.leftChild:
+                return self.leftChild.insert(data)
+            else:
+                self.leftChild = Node(data)
+                return True
+
+        else:
+            ''' Data greater than the root data is placed to the right of the root '''
+            if self.rightChild:
+                return self.rightChild.insert(data)
+            else:
+                self.rightChild = Node(data)
+                return True
+
+    def preorder(self):
+        '''For preorder traversal of the BST '''
+        if self:
+            print(str(self.data))
+            if self.leftChild:
+                self.leftChild.preorder()
+            if self.rightChild:
+                self.rightChild.preorder()
+
+    def inorder(self):
+        ''' For Inorder traversal of the BST '''
+        if self:
+            if self.leftChild:
+                self.leftChild.inorder()
+            print(str(self.data))
+            if self.rightChild:
+                self.rightChild.inorder()
+
+    def postorder(self):
+        ''' For postorder traversal of the BST '''
+        if self:
+            if self.leftChild:
+                self.leftChild.postorder()
+            if self.rightChild:
+                self.rightChild.postorder()
+            print(str(self.data))
+
+class Tree(object):
+    def __init__(self):
+        self.root = None
+
+    def insert(self, data):
+        if self.root:
+            return self.root.insert(data)
+        else:
+            self.root = Node(data)
+            return True
+
+    def preorder(self):
+        if self.root is not None:
+            print('Preorder: ')
+            self.root.preorder()
+
+    def inorder(self):
+        if self.root is not None:
+            print('Inorder: ')
+            self.root.inorder()
+
+    def postorder(self):
+        if self.root is not None:
+            print('Postorder: ')
+            self.root.postorder()
+
+if __name__ == '__main__':
+    tree = Tree()
+    tree.insert(10)
+    tree.insert(12)
+    tree.insert(5)
+    tree.insert(4)
+    tree.insert(20)
+    tree.insert(8)
+    tree.insert(7)
+    tree.insert(15)
+    tree.insert(13)
+    tree.preorder()
+    tree.inorder()
+    tree.postorder()