what is a binary tree used for code example

Example 1: binary tree

class Node:
    def __init__(self,key):
        self.left = None
        self.right = None
        self.val = key
 
root = Node(1)
root.left      = Node(2);
root.right     = Node(3);
root.left.left  = Node(4);

Example 2: binary tree in ds

# Python program to for tree traversals 

# A class that represents an individual node in a 
# Binary Tree 
class Node: 
	def __init__(self,key): 
		self.left = None
		self.right = None
		self.val = key 


# A function to do inorder tree traversal 
def printInorder(root): 

	if root: 

		# First recur on left child 
		printInorder(root.left) 

		# then print the data of node 
		print(root.val), 

		# now recur on right child 
		printInorder(root.right) 



# A function to do postorder tree traversal 
def printPostorder(root): 

	if root: 

		# First recur on left child 
		printPostorder(root.left) 

		# the recur on right child 
		printPostorder(root.right) 

		# now print the data of node 
		print(root.val), 


# A function to do preorder tree traversal 
def printPreorder(root): 

	if root: 

		# First print the data of node 
		print(root.val), 

		# Then recur on left child 
		printPreorder(root.left) 

		# Finally recur on right child 
		printPreorder(root.right) 


# Driver code 
root = Node(1) 
root.left	 = Node(2) 
root.right	 = Node(3) 
root.left.left = Node(4) 
root.left.right = Node(5) 
print "Preorder traversal of binary tree is"
printPreorder(root) 

print "\nInorder traversal of binary tree is"
printInorder(root) 

print "\nPostorder traversal of binary tree is"
printPostorder(root)