DoubleQueue.java

class MyCircularQueue {

 private int[] circleQueue; //queue
 
 private int front; //front pos
 
 private int rear; //rear pos
 
 private int size;
 
 
 /** Initialize your data structure here. Set the size of the queue to be k. */
 public MyCircularQueue(int k) {
 size = k;
 circleQueue = new int[size];
 front = -1;
 rear = -1;
 }
 
 /** Insert an element into the circular queue. Return true if the operation is successful. */
 public boolean enQueue(int value) {
 if (isFull()) {
 return false;
 }
 if (isEmpty()) {
 front = 0;
 }
 rear = (rear + 1) % size;
 circleQueue[rear] = value;
 return true;
 }
 
 /** Delete an element from the circular queue. Return true if the operation is successful. */
 public boolean deQueue() {
 if (isEmpty()) {
 return false;
 }
 if (front == rear) {
 front = -1;
 rear = -1;
 return true;
 }
 front = (front + 1) % size;
 return true;
 }
 
 /** Get the front item from the queue. */
 public int Front() {
 if (isEmpty()) {
 return -1;
 }
 return circleQueue[front];
 }
 
 /** Get the last item from the queue. */
 public int Rear() {
 if (isEmpty()) {
 return -1;
 }
 return circleQueue[rear];
 }
 
 /** Checks whether the circular queue is empty or not. */
 public boolean isEmpty() {
 return rear == -1;
 }
 
 /** Checks whether the circular queue is full or not. */
 public boolean isFull() {
 if (front == (rear + 1) % size) {
 return true;
 }
 return false;
 }

 public static void main(String[] args) {
 int k = 6;
 MyCircularQueue obj = new MyCircularQueue(k);
 System.out.println(obj.enQueue(6));
 System.out.println(obj.Rear());
 System.out.println(obj.Rear());
 obj.deQueue();
 boolean param_3 = obj.enQueue(5);
 System.out.println(param_3);
 System.out.println(obj.Rear());
 obj.deQueue();
 System.out.println(obj.Front());
 obj.deQueue();
 obj.deQueue();
 obj.deQueue();
 }
}