P64_DepthFirstTraversal.py

# Author: OMKAR PATHAK

# Depth first search is performed in three ways:
# Inorder
# Preorder
# Postorder

class Node(object):
    def __init__(self, data = None):
        self.left = None
        self.right = None
        self.data = data

    # for setting left node
    def setLeft(self, node):
        self.left = node

    # for setting right node
    def setRight(self, node):
        self.right = node

    # for getting the left node
    def getLeft(self):
        return self.left

    # for getting right node
    def getRight(self):
        return self.right

    # for setting data of a node
    def setData(self, data):
        self.data = data

    # for getting data of a node
    def getData(self):
        return self.data


# in this we traverse first to the leftmost node, then print its data and then traverse for rightmost node
def inorder(Tree):
    if Tree:
        inorder(Tree.getLeft())
        print(Tree.getData(), end = ' ')
        inorder(Tree.getRight())
    return

# in this we first print the root node and then traverse towards leftmost node and then to the rightmost node
def preorder(Tree):
    if Tree:
        print(Tree.getData(), end = ' ')
        preorder(Tree.getLeft())
        preorder(Tree.getRight())
    return

# in this we first traverse to the leftmost node and then to the rightmost node and then print the data
def postorder(Tree):
    if Tree:
        postorder(Tree.getLeft())
        postorder(Tree.getRight())
        print(Tree.getData(), end = ' ')
    return

if __name__ == '__main__':
    root = Node(1)
    root.setLeft(Node(2))
    root.setRight(Node(3))
    root.left.setLeft(Node(4))

    print('Inorder  Traversal:')
    inorder(root)
    print('\nPreorder Traversal:')
    preorder(root)
    print('\nPostorder Traversal:')
    postorder(root)

    # OUTPUT:
    # Inorder  Traversal:
    # 4 2 1 3
    # Preorder Traversal:
    # 1 2 4 3
    # Postorder Traversal:
    # 4 2 3 1