Write a short note on queue and priority queue.

Queue

A queue is a linear data structure that follows the First-In-First-Out (FIFO) principle, meaning that the first element added to the queue is the first one to be removed. Queues are often implemented using an array or a linked list. They have a wide range of applications, including managing tasks in a computer system, scheduling requests in a network, and handling waiting lines in a service system.

Operations:

• Enqueue: Adds an element to the rear (or tail) of the queue.
• Dequeue: Removes and returns the element at the front (or head) of the queue.
• Peek: Returns the element at the front of the queue without removing it.

Priority Queue

A priority queue is a queue in which elements are served based on their priority. Elements with higher priority are served before elements with lower priority. Priority queues are often implemented using a heap data structure. They have applications in various areas, such as scheduling processes in a computer system, managing tasks in a real-time system, and routing data packets in a network.

Operations:

• Enqueue: Adds an element to the priority queue, assigning it a priority.
• Dequeue: Removes and returns the element with the highest priority from the priority queue.
• Peek: Returns the element with the highest priority without removing it.

Comparison:

Feature	Queue	Priority Queue
Ordering	First-In-First-Out (FIFO)	Priority-based
Applications	Managing tasks in a computer system, scheduling requests in a network, handling waiting lines in a service system	Scheduling processes in a computer system, managing tasks in a real-time system, routing data packets in a network
Data Structure	Array or linked list	Heap
Efficiency	O(1) for enqueue and dequeue operations	O(log n) for enqueue and dequeue operations

Conclusion:

Queues and priority queues are fundamental data structures with a wide range of applications in computer science. Queues follow the FIFO principle, while priority queues serve elements based on their priority. The choice of data structure depends on the specific requirements of the problem being solved.