Stacks and queues are fundamental data structures in computer science, each serving distinct purposes based on their ordering principles. A stack operates on a Last In, First Out (LIFO) basis, where the most recently added element is the first to be removed. This structure supports operations like push (adding an element to the top) and pop (removing the top element), making it ideal for tasks such as undo functions in applications, function call stacks in programming, and parsing expressions.
In contrast, a queue follows a First In, First Out (FIFO) principle, where the earliest added element is the first to be removed. It includes operations like enqueue (adding an element to the rear) and dequeue (removing from the front), which are essential for scenarios like managing print jobs, handling network requests, and scheduling tasks in operating systems. While stacks excel in scenarios requiring reverse order processing, queues are perfect for orderly, sequential processing, highlighting their complementary roles in efficient data management.
Table of Contents
- Part 1: OnlineExamMaker AI Quiz Maker – Make A Free Quiz in Minutes
- Part 2: 20 Stacks & Queues Quiz Questions & Answers
- Part 3: AI Question Generator – Automatically Create Questions for Your Next Assessment
Part 1: OnlineExamMaker AI Quiz Maker – Make A Free Quiz in Minutes
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Part 2: 20 Stacks & Queues Quiz Questions & Answers
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1. Question: What is the primary characteristic of a stack data structure?
A. First In, First Out (FIFO)
B. Last In, First Out (LIFO)
C. First In, Last Out (FILO)
D. Last In, Last Out (LILO)
Answer: B
Explanation: A stack follows the LIFO principle, meaning the last element added is the first one to be removed, similar to a stack of plates.
2. Question: In a queue, which operation adds an element to the end?
A. Dequeue
B. Enqueue
C. Front
D. Rear
Answer: B
Explanation: Enqueue adds an element to the rear (end) of the queue, maintaining the FIFO order.
3. Question: If a stack is implemented using an array and is full, what occurs when you try to push another element?
A. Stack overflow
B. Stack underflow
C. Nothing, it adds successfully
D. The array resizes automatically
Answer: A
Explanation: Stack overflow happens when you attempt to add an element to a full stack, exceeding its allocated space.
4. Question: What is the time complexity of the push operation in a stack implemented with a linked list?
A. O(1)
B. O(n)
C. O(log n)
D. O(n log n)
Answer: A
Explanation: Pushing an element in a linked list-based stack involves adding to the top, which is a constant time operation.
5. Question: In a queue, which element is removed first in FIFO order?
A. The most recently added element
B. The least recently added element
C. A random element
D. The middle element
Answer: B
Explanation: FIFO ensures that the first element added (at the front) is the first one removed.
6. Question: How does a priority queue differ from a regular queue?
A. It follows LIFO
B. Elements are dequeued based on priority, not order
C. It only allows strings
D. It has no dequeue operation
Answer: B
Explanation: In a priority queue, elements are removed based on their priority levels rather than the order they were added.
7. Question: What happens when you pop from an empty stack?
A. Stack overflow
B. Stack underflow
C. Element is returned successfully
D. Queue operation is triggered
Answer: B
Explanation: Popping from an empty stack results in stack underflow, as there are no elements to remove.
8. Question: Which data structure is commonly used for implementing recursive function calls?
A. Queue
B. Stack
C. Array
D. Linked list
Answer: B
Explanation: Stacks are used to manage function calls and local variables in recursion due to their LIFO nature.
9. Question: In a circular queue, what is the purpose of the circular arrangement?
A. To make it LIFO
B. To reuse empty spaces after dequeue operations
C. To increase the queue size dynamically
D. To sort elements automatically
Answer: B
Explanation: A circular queue wraps around to the beginning when the end is reached, allowing efficient use of space.
10. Question: What is the main difference between a stack and a queue?
A. Stack uses arrays, queue uses linked lists
B. Stack is FIFO, queue is LIFO
C. Stack is LIFO, queue is FIFO
D. They have the same operations
Answer: C
Explanation: Stacks operate on LIFO, while queues operate on FIFO, making their element removal orders fundamentally different.
11. Question: Which operation in a queue retrieves the front element without removing it?
A. Enqueue
B. Dequeue
C. Front or Peek
D. Rear
Answer: C
Explanation: The front or peek operation allows viewing the front element of the queue without altering the structure.
12. Question: If you enqueue elements 1, 2, and 3 into a queue, in what order will they be dequeued?
A. 3, 2, 1
B. 1, 2, 3
C. 2, 1, 3
D. 3, 1, 2
Answer: B
Explanation: Due to FIFO, elements are dequeued in the order they were enqueued: first 1, then 2, then 3.
13. Question: What is a common application of stacks in programming?
A. Breadth-First Search (BFS)
B. Depth-First Search (DFS)
C. Scheduling tasks by priority
D. Managing network packets
Answer: B
Explanation: Stacks are used in DFS algorithms to explore as far as possible along each branch before backtracking.
14. Question: In an array-based queue, why might you need to shift elements during dequeue?
A. To maintain LIFO
B. To free up space at the front
C. Arrays don’t require shifting
D. To add new elements
Answer: B
Explanation: In a simple array implementation, dequeuing may require shifting elements to fill the gap, though circular queues avoid this.
15. Question: What is the worst-case time complexity for enqueue in a queue implemented with a linked list?
A. O(1)
B. O(n)
C. O(log n)
D. O(n^2)
Answer: A
Explanation: Enqueue in a linked list queue is typically O(1) if you maintain a reference to the rear node.
16. Question: Can a stack be used to reverse a string?
A. No, only queues can
B. Yes, by pushing characters and then popping them
C. Yes, but it requires sorting
D. No, stacks don’t handle strings
Answer: B
Explanation: Pushing characters of a string onto a stack and then popping them reverses the order due to LIFO.
17. Question: In a double-ended queue (deque), what operations are allowed?
A. Only enqueue at front
B. Enqueue and dequeue at both ends
C. Only dequeue at rear
D. No operations, it’s static
Answer: B
Explanation: A deque allows insertion and deletion at both the front and rear ends, making it more flexible than a standard queue.
18. Question: What error might occur if you try to dequeue from an empty queue?
A. Queue overflow
B. Queue underflow
C. Infinite loop
D. Segmentation fault
Answer: B
Explanation: Queue underflow occurs when attempting to remove an element from an empty queue.
19. Question: Which algorithm typically uses a queue for level-order traversal?
A. Binary Search Tree insertion
B. Breadth-First Search (BFS)
C. Merge Sort
D. Quick Sort
Answer: B
Explanation: BFS uses a queue to process nodes level by level, ensuring FIFO order for traversal.
20. Question: If a stack has elements [A, B, C] with C at the top, what will the stack look like after popping once?
A. [A, B, C]
B. [C, B, A]
C. [A, B]
D. [B, C, A]
Answer: C
Explanation: Popping removes the top element (C), leaving the stack as [A, B].
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