datastructurelaboratory/Queue.java at main · SRINIVASAN2001/datastructurelaboratory · GitHub

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import java.util.*;

class QNode {

    int key;

    QNode next;

    public QNode(int key)

    {

        this.key = key;

        this.next = null;

    }

}


class Queue {

    QNode front, rear;


    public Queue()

    {

        this.front = this.rear = null;

    }


    void enqueue(int key)

    {


        QNode temp = new QNode(key);

        if (this.rear == null) {

            this.front = this.rear = temp;

            return;

        }

        this.rear.next = temp;

        this.rear = temp;

    }


    void dequeue()

    {

        if (this.front == null)

            return;


        QNode temp = this.front;

        this.front = this.front.next;

        if (this.front == null)

            this.rear = null;

    }

}

public class Test {

    public static void main(String[] args)

    {

        Queue q = new Queue();

        q.enqueue(10);

        q.enqueue(20);

        q.dequeue();

        q.dequeue();

        q.enqueue(30);

        q.enqueue(40);

        q.enqueue(50);

        q.dequeue();

        System.out.println("Queue Front : " + q.front.key);

        System.out.println("Queue Rear : " + q.rear.key);

    }

}