Data Structures Questions Medium
A queue is a linear data structure that follows the First-In-First-Out (FIFO) principle. It is similar to a real-life queue or line, where the first person to join the queue is the first one to be served.
In a queue, elements are added at one end called the rear or tail, and removed from the other end called the front or head. This ensures that the element that has been in the queue the longest is the first one to be removed.
The process of adding an element to the queue is called enqueue, and it involves inserting the element at the rear end. When an element is enqueued, it becomes the new rear element. On the other hand, the process of removing an element from the queue is called dequeue, and it involves removing the element from the front end. When an element is dequeued, the element next in line becomes the new front element.
Queues can be implemented using arrays or linked lists. In an array implementation, a fixed-size array is used to store the elements, and two pointers, front and rear, are used to keep track of the positions of the front and rear elements. In a linked list implementation, each element is stored in a node, and the nodes are linked together to form the queue. The front and rear pointers point to the first and last nodes, respectively.
Queues are commonly used in various applications such as scheduling processes in operating systems, handling requests in web servers, and implementing breadth-first search algorithms. They provide an efficient way to manage elements in a sequential manner, ensuring that the order of insertion is preserved.