Queue Data Structure in C Programming
Queue Practice Questions
1. What is the time complexity of enqueue operation in a queue?
A) O(n)
B) O(log n)
C) O(1)
D) O(n log n)
Answer: C) O(1)
Enqueue operation in queue has constant time complexity when implemented properly, as it only involves adding an element at the rear.
2. Which principle does queue follow?
A) FIFO (First In First Out)
B) LIFO (Last In First Out)
C) FILO (First In Last Out)
D) LILO (Last In Last Out)
Answer: A) FIFO (First In First Out)
Queue follows FIFO principle where the first element added is the first one to be removed.
3. What happens when you try to dequeue from an empty queue?
A) Segmentation fault
B) Queue overflow
C) Queue underflow
D) Returns 0
Answer: C) Queue underflow
Attempting to dequeue from an empty queue results in queue underflow condition.
4. Which of these is NOT a valid queue operation?
A) Enqueue
B) Dequeue
C) Peek
D) Push
Answer: D) Push
Push is an operation of stack data structure, not queue.
5. What is the maximum number of queues needed to implement a stack?
A) 1
B) 2
C) 3
D) 4
Answer: B) 2
A stack can be implemented using two queues - either by making push operation costly or pop operation costly.
6. Which of the following applications typically uses queue?
A) CPU task scheduling
B) Breadth-first search
C) Printer job management
D) All of the above
Answer: D) All of the above
Queues are used in all these applications as they naturally model FIFO behavior needed in these scenarios.
7. In circular queue implementation, how do you calculate the next position of rear?
A) rear = (rear + 1) % capacity
B) rear = rear + 1
C) rear = capacity - 1
D) rear = (rear - 1) % capacity
Answer: A) rear = (rear + 1) % capacity
The modulo operation ensures the rear pointer wraps around to 0 when it reaches the end of the array.
8. What is the main advantage of circular queue over linear queue?
A) Faster enqueue operations
B) Better memory utilization
C) Easier implementation
D) No size limitation
Answer: B) Better memory utilization
Circular queue reuses the empty spaces created after dequeuing, while linear queue cannot.
9. What is the time complexity of searching for an element in a queue?
A) O(1)
B) O(log n)
C) O(n)
D) O(n log n)
Answer: C) O(n)
In worst case, you may need to examine all elements in the queue to find a specific one.
10. Which of the following is true about queue implementation using linked list?
A) Enqueue operation is always O(n)
B) Dequeue operation is always O(n)
C) Both enqueue and dequeue are O(1)
D) Queue size must be declared in advance
Answer: C) Both enqueue and dequeue are O(1)
In linked list implementation with proper head and tail pointers, both operations can be done in constant time.
11. What would be the queue configuration after these operations: enqueue(5), enqueue(3), dequeue(), enqueue(7), dequeue(), enqueue(9)?
A) [5, 7, 9]
B) [7, 9]
C) [9, 7]
D) [5, 3, 9]
Answer: B) [7, 9]
Operation sequence: enqueue(5)→[5], enqueue(3)→[5,3], dequeue()→[3], enqueue(7)→[3,7], dequeue()→[7], enqueue(9)→[7,9]
12. What is the condition for a circular queue to be considered full?
A) front == rear
B) (rear + 1) % size == front
C) rear == size - 1
D) front == 0
Answer: B) (rear + 1) % size == front
This condition checks if incrementing rear would make it equal to front, indicating the queue is full.
Related Queue Resources