Queues

In the world of programming and data structures, a queue is another common abstract data type. It is similar to a real-life queue or line, where people stand in a specific order and the first person who enters is the first person to leave.

A queue follows the FIFO (First-In, First-Out) principle. The elements are added at the rear end and removed from the front end. This makes a queue an ordered collection of elements.

Implementation of Queues

One common way to implement a queue is by using a linked list. The front of the queue is represented by the head node of the linked list, and the rear is represented by the tail node.

Here's an example of a queue implementation using Java:

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In the example above, we create a queue using the Queue interface from the Java Collections Framework. We add elements to the queue using the add method and remove elements using the remove method. The LinkedList class is used as the underlying implementation.

Common Operations on Queues

1. Enqueue: Adds an element to the rear end of the queue.
2. Dequeue: Removes and returns the element from the front end of the queue.
3. Front: Returns the element at the front end of the queue without removing it.
4. isEmpty: Checks if the queue is empty.

Queues have various applications in programming. They are commonly used in scheduling algorithms, operating systems, networking, and graph algorithms.

Now that you have a basic understanding of queues, let's move on to the next topic: Trees.

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class Main {

  public static void main(String[] args) {

    // replace with your Java logic here

    // Queue implementation using LinkedList

    Queue<String> queue = new LinkedList<>();

​

    // Adding elements to the queue

    queue.add("John");

    queue.add("Jane");

    queue.add("Alice");

​

    // Printing the queue

    System.out.println("Elements in the Queue: " + queue);

​

    // Removing elements from the queue

    String removedElement = queue.remove();

    System.out.println("Removed Element: " + removedElement);

​

    // Printing the updated queue

    System.out.println("Elements in the Queue after removal: " + queue);

  }

}