Binary Search Tree
Create Root
We just create a Node class and add assign a value to the node. This becomes tree with only a root node.
class Node:
def __init__(self, data):
self.left = None
self.right = None
self.data = data
def PrintTree(self):
print(self.data)
root = Node(10)
root.PrintTree()
Inserting into a Tree
To insert into a tree we use the same node class created above and add an insert method to it The insert method compares the value of the node to the parent node and decides to add it as a left node or a right node. Finally, the PrintTree method is used to print the tree.
class Node:
def __init__(self, data):
self.left = None
self.right = None
self.data = data
def insert(self, data):
# Compare the new value with the parent node
if self.data:
if data < self.data:
if self.left is None:
self.left = Node(data)
else:
self.left.insert(data)
elif data > self.data:
if self.right is None:
self.right = Node(data)
else:
self.right.insert(data)
else:
self.data = data
# Print the tree
def PrintTree(self):
if self.left:
self.left.PrintTree()
print( self.data),
if self.right:
self.right.PrintTree()
# Use the insert method to add nodes
root = Node(12)
root.insert(6)
root.insert(14)
root.insert(3)
root.PrintTree()
Traversals of Binary Tree
# Inorder traversal
# Left -> Root -> Right
class Node:
def __init__(self, data):
self.left = None
self.right = None
self.data = data
# Insert Node
def insert(self, data):
if self.data:
if data < self.data:
if self.left is None:
self.left = Node(data)
else:
self.left.insert(data)
elif data > self.data:
if self.right is None:
self.right = Node(data)
else:
self.right.insert(data)
else:
self.data = data
# Print the Tree
def PrintTree(self):
if self.left:
self.left.PrintTree()
print( self.data),
if self.right:
self.right.PrintTree()
def inorderTraversal(self, root):
res = []
if root:
res = self.inorderTraversal(root.left)
res.append(root.data)
res = res + self.inorderTraversal(root.right)
return res
root = Node(27)
root.insert(14)
root.insert(35)
root.insert(10)
root.insert(19)
root.insert(31)
root.insert(42)
print(root.inorderTraversal(root))