This set of Data Structure Multiple Choice Questions & Answers (MCQs) focuses on “Threaded Binary Tree”.
1. What is a threaded binary tree traversal?
a) a binary tree traversal using stacks
b) a binary tree traversal using queues
c) a binary tree traversal using stacks and queues
d) a binary tree traversal without using stacks and queues
Explanation: This type of tree traversal will not use stack or queue.
2. What are the disadvantages of normal binary tree traversals?
a) there are many pointers which are null and thus useless
b) there is no traversal which is efficient
c) complexity in implementing
d) improper traversals
Explanation: As there are majority of pointers with null value going wasted we use threaded binary trees.
3. What may be the content of a node in threaded binary tree?
a) leftchild_pointer, left_tag, data, right_tag, rightchild_pointer
b) leftchild_pointer, left_tag
c) leftchild_pointer, left_tag, right_tag, rightchild_pointer
d) leftchild_pointer, left_tag, data
Explanation: It contains additional 2 pointers over normal binary tree node structure.
4. What are null nodes filled with in a threaded binary tree?
a) inorder predecessor for left node and inorder successor for right node information
b) right node with inorder predecessor and left node with inorder successor information
c) they remain null
d) some other values randomly
Explanation: If preorder or postorder is used then the respective predecessor and successor info is stored.
5. The null left pointer pointing to predecessor and null right pointer pointing to successor. how many types of threaded tree are possible with this convention?
a) inorder, postorder, preorder traversals
Explanation: Those are the three representations of binary threaded trees.
6. What are double and single threaded trees?
a) when both left, right nodes are having null pointers and only right node is null pointer respectively
b) having 2 and 1 node
c) using single and double linked lists
d) using heaps and priority queues
Explanation: They are properties of double and single threaded binary trees respectively.
7. What is wrong with below code for inorder traversal of inorder threaded binary tree:
inordertraversal(threadedtreenode root): threadedtreenode q = inorderpredecessor(root) while(q!=root): q=inorderpredecessor(q) print q.data
a) inordersuccessor instead of inorderpredecessor must be done
b) code is correct
c) it is code for post order
d) it is code for pre order
Explanation: Property of inorder threaded binary tree is left node with inorder predecessor and right node with inorder successor information are stored.
Explanation: The nodes extreme left and right are pointing to nothing which could be also used efficiently.
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