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Java-based LeetCode algorithm problem solutions, regularly updated

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641\. Design Circular Deque

Medium

Design your implementation of the circular double-ended queue (deque).

Implement the `MyCircularDeque` class:

*   `MyCircularDeque(int k)` Initializes the deque with a maximum size of `k`.
*   `boolean insertFront()` Adds an item at the front of Deque. Returns `true` if the operation is successful, or `false` otherwise.
*   `boolean insertLast()` Adds an item at the rear of Deque. Returns `true` if the operation is successful, or `false` otherwise.
*   `boolean deleteFront()` Deletes an item from the front of Deque. Returns `true` if the operation is successful, or `false` otherwise.
*   `boolean deleteLast()` Deletes an item from the rear of Deque. Returns `true` if the operation is successful, or `false` otherwise.
*   `int getFront()` Returns the front item from the Deque. Returns `-1` if the deque is empty.
*   `int getRear()` Returns the last item from Deque. Returns `-1` if the deque is empty.
*   `boolean isEmpty()` Returns `true` if the deque is empty, or `false` otherwise.
*   `boolean isFull()` Returns `true` if the deque is full, or `false` otherwise.

**Example 1:**

**Input** 

["MyCircularDeque", "insertLast", "insertLast", "insertFront", "insertFront", "getRear", "isFull", "deleteLast", "insertFront", "getFront"] 

[[3], [1], [2], [3], [4], [], [], [], [4], []]

**Output:** [null, true, true, true, false, 2, true, true, true, 4]

**Explanation:** 

MyCircularDeque myCircularDeque = new MyCircularDeque(3); 

myCircularDeque.insertLast(1); // return True 

myCircularDeque.insertLast(2); // return True 

myCircularDeque.insertFront(3); // return True 

myCircularDeque.insertFront(4); // return False, the queue is full. 

myCircularDeque.getRear(); // return 2 

myCircularDeque.isFull(); // return True 

myCircularDeque.deleteLast(); // return True 

myCircularDeque.insertFront(4); // return True 

myCircularDeque.getFront(); // return 4

**Constraints:**

*   `1 <= k <= 1000`
*   `0 <= value <= 1000`
*   At most `2000` calls will be made to `insertFront`, `insertLast`, `deleteFront`, `deleteLast`, `getFront`, `getRear`, `isEmpty`, `isFull`.