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g0601_0700.s0622_design_circular_queue.readme.md Maven / Gradle / Ivy

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`.