Two marks Questions with Answers

Two Marks Questions with Answers

Q.1 What do the terms LIFO and FIFO means? Explain.

Ans. : The LIFO stands for Last In First Out. This property belongs to stack. That means the element inserted lastly will be the element to be popped off first from the stack.

The FIFO stands for First In First Out. This property belongs to queue. That means the element inserted first in the queue will be the first to get deleted.

Q.2 What are the front and rear pointers of queue.

Ans. : The front end of the queue from which the element gets deleted is called front and the end from which the element is inserted in the queue is called rear.

For example: Refer Fig. 

Q.3 What is a circular queue?

Ans. : Circular queue is a queue in which the front end is just adjacent to the rear end. The elements get arranged in circular manner. For example - Refer Fig. 

Q.4 Write any four applications of queues.

Ans;

1. In operating system for scheduling jobs, priority queues are used.

2. In Local Area Network (LAN) multiple computers share few printers. Then these printers accumulate jobs in a queue. Thus printers can process multiple print commands with the help of queues.

3. For categorizing data, queues are used.

4. In simulation and modeling queues are used.

5. In computer networks, while broadcasting message, the message packets are accumulated in queue. And then these packets are forwarded.

Q.5 What is a dequeue?

Ans. : The dequeue is a data structure in which the element can be inserted from both the ends i.e. front and rear. Similarly, the element can be deleted from both the front and rear end.

Q.6 How do you test for an empty queue?

Ans. Following is a C code which is used to test an empty queue

if((Q.front==-1) | | (Q.front>Q.rear))

printf("\n The Queue is Empty!!");

else

printf("\n The Queue is not Empty!!")

Q.7 What is the use of queue in operating system?

Ans. : The queue is used for scheduling the jobs in operating system.

Q.8What is the need for circular queue ?

Ans.

The circular queue is an useful data structure in which all the cells of the queue can be utilized. Secondly due to circular queue one can traverse to the first node from the last node very efficiently.

Q.9 What is stack and Queue ?

Ans. : Stack is linear data structure in which insertion and deletion of element is from one end called top.

Queue is a linear data structure in which insertion of element is from one end called rear and deletion of element is from other end called front.

Q.10 What are priority queues? What are the ways to implement priority queue ?

Ans. 

 Definition: The priority queue is a data structure having a collection of elements which are associated with specific ordering.

•Ways to implement Priority Queue:

There are two ways to implement priority queue.

1. Ascending Priority Queue - It is a collection of items in which the items can be inserted arbitarily but only smallest element can be removed.

2. Descending Priority Queue - It is a collection of items in which insertion of items can be in any order but only largest element can be removed.

Q.11 A priority queue is impletemented as Max heap. Initially it has 5 elements. The level order traversal of heap is: 10, 8, 5, 3, 2. Two new elements 11 and 7 are inserted into the heap in that order. Give level order traversal of the heap after the insertion of elements.

Ans. Step 1: The heap is as shown below.

Step 2: The level order after insertion of given elements is 11, 8, 10, 3, 2, 7.