# Data Structure Questions and Answers-Priority Queue

## Data Structure Questions and Answers-Priority Queue

 Question 1 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
With what data structure can a priority queue be implemented?
 A Array B List C Heap D All of the mentioned
Question 1 Explanation:
Priority queue can be implemented using an array, a list, a binary search tree or a heap, although the most efficient one being the heap.

 Question 2 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Which of the following is not an application of priority queue?
 A Huffman codes B Interrupt handling in operating system C Undo operation in text editors D Bayesian spam filter
Question 2 Explanation:
Undo operation is achieved using a stack.

 Question 3 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Select the appropriate code that inserts elements into the list based on the given key value.

(head and trail are dummy nodes to mark the end and beginning of the list, they do not contain any priority or element)

 A `public void insert....key(int key, Object item) { if(key<0) { Systerm.our.println("invalid"); System.exit(0)` B `public void insert....key(int key, Object item) { if(key<0) { Systerm.our.println("invalid"); System.exit(0)public void insert....key(int key, Object item) { if(key<0) { Systerm.our.println("invalid"); System.exit(0)` D None of the mentioned
Question 3 Explanation:
Have two temporary pointers 'dup' and 'cur' with 'cur' trailing behind 'dup'. Traverse through the list until the given key is greater than some element with a lesser key, insert the new node 'temp' in that position.

 Question 4 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
What is the time complexity to insert a node based on key in a priority queue?
 A O(nlogn) B O(logn) C O(n) D O(n2)
Question 4 Explanation:
In the worst case, you might have to traverse the entire list.

 Question 5 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
What is the functionality of the following piece of code?

`public Object delete....key() { 	if(count == 0) 	{ 		System.out.println("Q is empty"); 		System.exit(0); 	} 	else 	{ 		Node cur = head.getNext(); 		Node dup = cur.getNext(); 		Object e = cur.getEle(); 		head.setNext(dup); 		count--; 		return e; 	} }`
 A Delete the second element in the list B Return but not delete the second element in the list C Delete the first element in the list D Return but not delete the first element in the list
Question 5 Explanation:
A pointer is made to point at the first element in the list and one more to point to the second element, pointer manipulations are done such that the first element is no longer being pointed by any other pointer, its value is returned.

There are 5 questions to complete.