postorder_tree_traversal.py

# 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)