Design Circular Queue

Design your implementation of the circular queue. The circular queue is a linear data structure in which the operations are performed based on FIFO (First In First Out) principle and the last position is connected back to the first position to make a circle. It is also called "Ring Buffer".

One of the benefits of the circular queue is that we can make use of the spaces in front of the queue. In a normal queue, once the queue becomes full, we cannot insert the next element even if there is a space in front of the queue. But using the circular queue, we can use the space to store new values.

Your implementation should support following operations:

• MyCircularQueue(k): Constructor, set the size of the queue to be k.
• Front: Get the front item from the queue. If the queue is empty, return -1.
• Rear: Get the last item from the queue. If the queue is empty, return -1.
• enQueue(value): Insert an element into the circular queue. Return true if the operation is successful.
• deQueue(): Delete an element from the circular queue. Return true if the operation is successful.
• isEmpty(): Checks whether the circular queue is empty or not.
• isFull(): Checks whether the circular queue is full or not.

Example:

MyCircularQueue circularQueue = new MyCircularQueue(3); // set the size to be 3
circularQueue.enQueue(1);  // return true
circularQueue.enQueue(2);  // return true
circularQueue.enQueue(3);  // return true
circularQueue.enQueue(4);  // return false, the queue is full
circularQueue.Rear();  // return 3
circularQueue.isFull();  // return true
circularQueue.deQueue();  // return true
circularQueue.enQueue(4);  // return true
circularQueue.Rear();  // return 4

 class MyCircularQueue {
     final int[] a;
     int front, rear = -, len = ;

     public MyCircularQueue(int k) {
         a = new int[k];
     }

     public boolean enQueue(int val) {
         if (!isFull()) {
             rear = (rear + ) % a.length;
             a[rear] = val;
             len++;
             return true;
         } else {
             return false;
         }
     }

     public boolean deQueue() {
         if (!isEmpty()) {
             front = (front + ) % a.length;
             len--;
             return true;
         } else
             return false;
     }

     public int Front() {
         return isEmpty() ? - : a[front];
     }

     public int Rear() {
         return isEmpty() ? - : a[rear];
     }

     public boolean isEmpty() {
         return len == ;
     }

     public boolean isFull() {
         return len == a.length;
     }
 }