Prepare for Queue Data Structure Interview with iQwizz | Difficulty Level: Advance | Rating: 4.2

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Question 1

Imagine you need to design a system for handling requests with different priority levels. High-priority requests should be processed before lower-priority ones. Which queue implementation would be best suited for this scenario?

A LIFO queue (stack)
A priority queue
A circular queue
A standard FIFO queue

Question 2

You need to implement a queue with the following operations: enqueue, dequeue, and find the minimum element in the queue in O(1) time complexity. Which data structure would be most efficient for this scenario?

A single queue
A queue and a min-heap
Two queues
A queue and a stack

Question 3

Consider a circular queue implemented using an array. If the front is at index 5 and the rear is at index 2 (with a valid queue configuration), what is the current size of the queue (assuming the array has a capacity greater than the queue size)?

Cannot be determined with the given information
3
7
4

Question 4

Which queue implementation is generally preferred when you need to prioritize elements based on certain criteria, leading to elements being dequeued out of their standard FIFO order?

Linked list-based queue
None of the above
Circular queue
Array-based queue

Question 5

Imagine you need to implement a system that keeps track of the last N requests made to a server, along with their timestamps. This data is used for monitoring and analyzing recent server activity. Which deque operation would be MOST frequently used for maintaining this sliding window of requests?

front()
push_back()
pop_front()
push_front()

Question 6

A palindrome is a word or phrase that reads the same backward as forward. You are tasked with designing an algorithm to check if a given string is a palindrome, ignoring spaces and case. How could a deque be used effectively in your algorithm?

Push each character of the string onto a deque and then pop them off, comparing the popped characters.
Use two deques, one for the original string and one for its reverse, and compare them element by element.
A deque is not a suitable data structure for checking palindromes.
Store the entire string in a deque and compare elements from both ends towards the middle.

Question 7

In a circular queue implemented with an array of size 5, if front = 2 and rear = 4, what will be the new values of front and rear after two dequeue operations, followed by one enqueue operation?

front = 0, rear = 1
front = 1, rear = 2
front = 4, rear = 0
front = 3, rear = 0

Question 8

You are building a system to manage a print queue for a network printer. Multiple computers can send print jobs (represented as objects) to the queue. Which feature of a deque would be MOST beneficial for allowing users to prioritize urgent print jobs?

The ability to insert elements at the front (push_front())
Random access to elements in the deque
Constant time complexity for accessing the last element (back())
The ability to iterate through the deque in reverse order

Question 9

You are designing a text editor with an undo/redo functionality. You want to store the history of operations efficiently, allowing the user to undo and redo actions in any order. Which data structure, built using deques, is best suited for this scenario?

A single deque where undo operations are stored at the front and redo operations at the back
A deque of deques, where each inner deque represents a state of the text editor
A deque is not suitable for this scenario
Two separate deques, one for undo and one for redo

Question 10

Consider two queues: Q1 implemented using a singly linked list and Q2 implemented using a circular array. Both queues currently hold n elements. What is the difference in time complexity for dequeuing all elements from Q1 and Q2?

Q1 has O(n^2) complexity, Q2 has O(n) complexity
Q1 has O(n) complexity, Q2 has O(1) complexity
Both have the same time complexity, O(n)
Q1 has O(n) complexity, Q2 has O(n^2) complexity

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Question 1

A LIFO queue (stack)
A priority queue
A circular queue
A standard FIFO queue

Question 2

A single queue
A queue and a min-heap
Two queues
A queue and a stack

Question 3

Cannot be determined with the given information
3
7
4

Question 4

Which queue implementation is generally preferred when you need to prioritize elements based on certain criteria, leading to elements being dequeued out of their standard FIFO order?

Linked list-based queue
None of the above
Circular queue
Array-based queue

Question 5

front()
push_back()
pop_front()
push_front()

Question 6

Push each character of the string onto a deque and then pop them off, comparing the popped characters.
Use two deques, one for the original string and one for its reverse, and compare them element by element.
A deque is not a suitable data structure for checking palindromes.
Store the entire string in a deque and compare elements from both ends towards the middle.

Question 7

In a circular queue implemented with an array of size 5, if front = 2 and rear = 4, what will be the new values of front and rear after two dequeue operations, followed by one enqueue operation?

front = 0, rear = 1
front = 1, rear = 2
front = 4, rear = 0
front = 3, rear = 0

Question 8

The ability to insert elements at the front (push_front())
Random access to elements in the deque
Constant time complexity for accessing the last element (back())
The ability to iterate through the deque in reverse order

Question 9

A single deque where undo operations are stored at the front and redo operations at the back
A deque of deques, where each inner deque represents a state of the text editor
A deque is not suitable for this scenario
Two separate deques, one for undo and one for redo

Question 10

Q1 has O(n^2) complexity, Q2 has O(n) complexity
Q1 has O(n) complexity, Q2 has O(1) complexity
Both have the same time complexity, O(n)
Q1 has O(n) complexity, Q2 has O(n^2) complexity

Queue Data Structure Questions

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