Package g0601_0700.s0622_design_circular_queue

Class MyCircularQueue

  • public class MyCircularQueue
extends Object
    622 - Design Circular Queue.

    Medium

    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.

    Implementation the MyCircularQueue class:

    • MyCircularQueue(k) Initializes the object with the size of the queue to be k.
    • int Front() Gets the front item from the queue. If the queue is empty, return -1.
    • int Rear() Gets the last item from the queue. If the queue is empty, return -1.
    • boolean enQueue(int value) Inserts an element into the circular queue. Return true if the operation is successful.
    • boolean deQueue() Deletes an element from the circular queue. Return true if the operation is successful.
    • boolean isEmpty() Checks whether the circular queue is empty or not.
    • boolean isFull() Checks whether the circular queue is full or not.

    You must solve the problem without using the built-in queue data structure in your programming language.

    Example 1:

    Input [“MyCircularQueue”, “enQueue”, “enQueue”, “enQueue”, “enQueue”, “Rear”, “isFull”, “deQueue”, “enQueue”, “Rear”] [[3], [1], [2], [3], [4], [], [], [], [4], []]

    Output: [null, true, true, true, false, 3, true, true, true, 4]

    Explanation: MyCircularQueue myCircularQueue = new MyCircularQueue(3); myCircularQueue.enQueue(1); // return True myCircularQueue.enQueue(2); // return True myCircularQueue.enQueue(3); // return True myCircularQueue.enQueue(4); // return False myCircularQueue.Rear(); // return 3 myCircularQueue.isFull(); // return True myCircularQueue.deQueue(); // return True myCircularQueue.enQueue(4); // return True myCircularQueue.Rear(); // return 4

    Constraints:

    • 1 <= k <= 1000
    • 0 <= value <= 1000
    • At most 3000 calls will be made to enQueue, deQueue, Front, Rear, isEmpty, and isFull.

    • Constructor Detail

      • MyCircularQueue

        public MyCircularQueue​(int k)

    • Method Detail

      • enQueue

        public boolean enQueue​(int value)

      • deQueue

        public boolean deQueue()

      • rear

        public int rear()

      • front

        public int front()

      • isEmpty

        public boolean isEmpty()

      • isFull

        public boolean isFull()