Question 16: What is the significance of the front pointer in a queue?
Solution :
The front pointer in a queue tracks the position of the element to be dequeued next. After each dequeue operation, the front pointer is incremented. In a circular queue, when the front pointer reaches the end of the array, it wraps around to the beginning.
Question 17: Describe how the queue is used in a round-robin scheduling algorithm.
Solution :
In a round-robin scheduling algorithm, a queue is used to manage processes. Each process is added to the queue and given a time slice to execute. After its time slice is over, the process is moved to the rear of the queue, and the next process at the front is given the CPU. This ensures fair allocation of resources.
Question 18: What is the space complexity of a queue implemented using a linked list?
Solution :
The space complexity of a queue implemented using a linked list is O(n), where n is the number of elements in the queue. Each node in the linked list requires space for storing the data and the reference to the next node.
Question 19: How can you detect whether a queue is full in a circular queue implementation?
Solution :
In a circular queue, the queue is full when the next position of the rear pointer equals the front pointer (i.e., (rear + 1) % size == front). This indicates that all positions are occupied and no more elements can be added until some are removed.
Question 20: Write two real-world examples of a queue data structure.
Solution :
1. A line of customers waiting at a bank teller.
2. A queue of
packets waiting to be processed by a router in a network.
Question 21: Explain why a queue is suitable for breadth-first search (BFS) in graph traversal.
Solution :
In BFS, nodes are visited in the order of their distance from the starting node. A queue is suitable because it maintains the order of nodes, ensuring that the first node visited is the first one whose neighbors are explored. This maintains the level-order exploration, as required by BFS.
Question 22: What is the time complexity of checking whether a queue is empty?
Solution :
The time complexity of checking whether a queue is empty is O(1). This operation typically involves comparing the front and rear pointers to see if they indicate an empty queue.
Question 23: How can a priority queue be implemented using a regular queue?
Solution :
A priority queue can be implemented using a regular queue by inserting elements into the queue based on their priority. Instead of always adding elements to the rear, elements are inserted in the appropriate position such that the highest-priority element is at the front of the queue.
Question 24: Why is a queue not suitable for depth-first search (DFS)?
Solution :
A queue is not suitable for DFS because it explores nodes in FIFO order, which is not compatible with the depth-first nature of DFS. DFS requires a LIFO structure (stack) to explore nodes deeper in the graph before returning to previous levels, while a queue would explore nodes level by level, like in BFS.
Question 25: Give a situation where a double-ended queue (deque) would be useful.
Solution :
A double-ended queue (deque) is useful in a scenario like a sliding window in real-time analytics, where elements need to be added or removed from both ends of a data stream. For example, in tracking the highest temperature in the past hour, a deque can be used to quickly add new temperature readings and remove old ones from both ends.
Question 26: What happens if you try to enqueue an element in a full queue?
Solution :
If you try to enqueue an element in a full queue, it will result in an overflow condition. In such cases, there is no available space to add the new element, and the operation cannot be performed. Proper error handling should be implemented to avoid overflow issues.
Question 27: Explain the role of a queue in a printer spooler system.
Solution :
In a printer spooler system, print jobs are stored in a queue. The first job added to the queue is printed first (FIFO). New print jobs are added to the rear of the queue, while the printer processes jobs from the front. This ensures that jobs are printed in the order they were submitted.
Question 28: How does a queue help in load balancing?
Solution :
In load balancing, a queue is used to distribute tasks among multiple servers. Incoming tasks are added to the queue, and each server processes tasks from the front of the queue. This ensures an even distribution of workload and prevents any one server from becoming overloaded.
Question 29: Describe the working of a queue in an elevator system.
Solution :
In an elevator system, floors requested by users are added to a queue. The elevator processes requests in a sequential manner, visiting the floors in the order they were added (FIFO). This ensures fairness in serving the floors and avoids skipping over floors requested earlier.
Question 30: What is the significance of the modulo operator in a circular queue?
Solution :
The modulo operator is used in a circular queue to wrap the front and rear pointers around when they reach the end of the queue. This ensures that the pointers stay within the bounds of the array and effectively make the queue circular (i.e., rear = (rear + 1) % size).