Java Program to Rotate a queue by ‘K’ position

              Queue is a linear data structure. It has a front end which points out the beginning and rear end which points out the ending of the queue.

Generally, deletion occurs in front end. Insertions occurs in rear end.

Process:

• First , a java class is written with a constructor.  x
• We create a queue as linked list and declare an object instance.
• The constructor checks the ‘k’ value and rotates the queue by moving the front end element to rear end until the ‘k’th element as front end.
• Inside the main function, create an object for queue. The data’s are inserted in the queue.
• The input value is received from user. The queue object and k value is passed to the function.
• The function returns the rotated queue  and it is displayed in the output screen.

Program:

import java.util.LinkedList;

import java.util.Queue;

import java.util.Scanner;

public class RotateaQueue {

    // function definition for rotation

    public static void rotateaQueue(Queue<Integer> queue1, int k) {

        int q_size = queue1.size();

        k = k % q_size;

        for (int i = 0; i < k; i++) {

            // Let us move the frontend element to the rearend

            int frontend = queue1.poll();

            queue1.add(frontend);

        }

    }

    public static void main(String[] args) {

        Queue<Integer> queue1 = new LinkedList<>();

        Scanner myObj1 = new Scanner(System.in);

        queue1.add(11);

        queue1.add(32);

        queue1.add(25);

        queue1.add(40);

        queue1.add(15);

        queue1.add(20);

        System.out.println("Enter the K value from which the queue is going to be rotated:");

        int k= myObj1.nextInt();

        System.out.println("Original Queue: " + queue1);

        rotateaQueue(queue1, k);

        System.out.println("Rotated Queue: " + queue1);

    }

}

Output:

C:\raji\blog>java RotateaQueue

Enter the K value from which the queue is going to be rotated:

4

Original Queue: [11, 32, 25, 40, 15, 20]

Rotated Queue: [15, 20, 11, 32, 25, 40]

That’s all. The java program to implement the rotatation of  a queue by k positions is running successfully. Keep coding!!!