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tree.py
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# Author: OMKAR PATHAK
# Created On: 9th August 2017
# Node class to create a node for binary tree
class Node(object):
def __init__(self, data = None):
self.left = None
self.right = None
self.data = data
def set_left(self, node):
''' for setting the left child of the node '''
self.left = node
def set_right(self, node):
''' for setting the right child of the node '''
self.right = node
def get_left(self):
''' for getting the left child of the node '''
return self.left
def get_right(self):
''' for getting the right child of the node '''
return self.right
def set_data(self, data):
''' for setting the data of the node '''
self.data = data
def get_data(self):
''' for getting the data of the node '''
return self.data
# easily retrieve the source code of the Node class
def get_code(self):
''' returns the code of the current class '''
import inspect
return inspect.getsource(Node)
# BinaryTree class to create a binary tree
class BinaryTree(object):
def __init__(self):
self._inorder = []
self._preorder = []
self._postorder = []
# in this we traverse first to the leftmost node, then print its data and then traverse for rightmost node
def inorder(self, root):
'''
@type: root: Node object
'''
if root:
self.inorder(root.get_left()) # traverse to leftmost child
self._inorder.append(root.get_data()) # get the data of current node
self.inorder(root.get_right()) # traverse to rightmost child
return self._inorder
# in this we first print the root node and then traverse towards leftmost node and then to the rightmost node
def preorder(self, root):
'''
@type: root: Node object
'''
if root:
self._preorder.append(root.get_data()) # get the data of current node
self.preorder(root.get_left()) # traverse to leftmost child
self.preorder(root.get_right()) # traverse to rightmost child
return self._preorder
# in this we first traverse to the leftmost node and then to the rightmost node and then print the data
def postorder(self, root):
'''
@type: root: Node object
'''
if root:
self.postorder(root.get_left()) # traverse to leftmost child
self.postorder(root.get_right()) # traverse to rightmost child
self._postorder.append(root.get_data()) # get the data of current node
return self._postorder
# easily retrieve the source code of the BinaryTree class
def get_code(self):
''' returns the code of the current class '''
import inspect
return inspect.getsource(BinaryTree)
class BSTNode(object):
def __init__(self, data):
self.data = data
self.leftChild = None
self.rightChild = None
self._inorder = []
self._preorder = []
self._postorder = []
def set_left(self, node):
''' for setting the left child of the node '''
self.leftChild = node
def set_right(self, node):
''' for setting the right child of the node '''
self.rightChild = node
def get_left(self):
''' returns the left child of the current node '''
return self.leftChild
def get_right(self):
''' returns the right child of the current node '''
return self.rightChild
# for setting data of a node
def set_data(self, data):
''' for setting the data of a node '''
self.data = data
# for getting data of a node
def get_data(self):
''' returns the data of the current node '''
return self.data
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 = BSTNode(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 = BSTNode(data)
return True
def min_val_bst_node(self, BSTNode):
current = BSTNode
# loop down to find the leftmost leaf
while(current.leftChild is not None):
current = current.leftChild
return current
def delete(self, data):
''' For deleting the BSTNode '''
if self is None:
return root
# if current BSTNode's data is less than that of root BSTNode, then only search in left subtree else right subtree
if data < self.data:
self.leftChild = self.leftChild.delete(data)
elif data > self.data:
self.rightChild = self.rightChild.delete(data)
else:
# deleting BSTNode with one child
if self.leftChild is None:
temp = self.rightChild
self = None
return temp
elif self.rightChild is None:
temp = self.leftChild
self = None
return temp
# deleting BSTNode with two children
# first get the inorder successor
temp = self.min_val_bst_node(self.rightChild)
self.data = temp.data
self.rightChild = self.rightChild.delete(temp.data)
return self
def find(self, data):
''' This function checks whether the specified data is in tree or not '''
if(data == self.data):
return True
elif(data < self.data):
if self.leftChild:
return self.leftChild.find(data)
else:
return False
else:
if self.rightChild:
return self.rightChild.find(data)
else:
return False
def inorder(self, root):
'''
@type: root: Node object
'''
if root:
self.inorder(root.get_left()) # traverse to leftmost child
self._inorder.append(root.get_data()) # get the data of current node
self.inorder(root.get_right()) # traverse to rightmost child
return self._inorder
# in this we first print the root node and then traverse towards leftmost node and then to the rightmost node
def preorder(self, root):
'''
@type: root: Node object
'''
if root:
self._preorder.append(root.get_data()) # get the data of current node
self.preorder(root.get_left()) # traverse to leftmost child
self.preorder(root.get_right()) # traverse to rightmost child
return self._preorder
# in this we first traverse to the leftmost node and then to the rightmost node and then print the data
def postorder(self, root):
'''
@type: root: Node object
'''
if root:
self.postorder(root.get_left()) # traverse to leftmost child
self.postorder(root.get_right()) # traverse to rightmost child
self._postorder.append(root.get_data()) # get the data of current node
return self._postorder
# easily retrieve the source code of the BSTNode class
def get_code(self):
''' returns the code of current class '''
import inspect
return inspect.getsource(BSTNode)
class BinarySearchTree(object):
def __init__(self):
self.root = None
def insert(self, data):
''' inserts a node in the tree '''
if self.root:
return self.root.insert(data)
else:
self.root = BSTNode(data)
return True
def delete(self, data):
''' deletes the node with the specified data from the tree '''
if self.root is not None:
return self.root.delete(data)
def find(self, data):
if self.root:
return self.root.find(data)
else:
return False
def preorder(self):
''' finding the preorder of the tree '''
if self.root is not None:
return self.root.preorder(self.root)
def inorder(self):
''' finding the inorder of the tree '''
print()
if self.root is not None:
return self.root.inorder(self.root)
def postorder(self):
''' finding the postorder of the tree '''
print()
if self.root is not None:
return self.root.postorder(self.root)
# easily retrieve the source code of the BinarySearchTree class
def get_code(self):
''' returns the code of the current class '''
import inspect
return inspect.getsource(BinarySearchTree)