LC 641. Design Circular Deque

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

Your implementation should support following operations:

• MyCircularDeque(k): Constructor, set the size of the deque to be k.
• insertFront(): Adds an item at the front of Deque. Return true if the operation is successful.
• insertLast(): Adds an item at the rear of Deque. Return true if the operation is successful.
• deleteFront(): Deletes an item from the front of Deque. Return true if the operation is successful.
• deleteLast(): Deletes an item from the rear of Deque. Return true if the operation is successful.
• getFront(): Gets the front item from the Deque. If the deque is empty, return -1.
• getRear(): Gets the last item from Deque. If the deque is empty, return -1.
• isEmpty(): Checks whether Deque is empty or not. 
• isFull(): Checks whether Deque is full or not.

 

Example:

MyCircularDeque circularDeque = new MycircularDeque(3); // set the size to be 3
circularDeque.insertLast(1);			// return true
circularDeque.insertLast(2);			// return true
circularDeque.insertFront(3);			// return true
circularDeque.insertFront(4);			// return false, the queue is full
circularDeque.getRear();  			// return 2
circularDeque.isFull();				// return true
circularDeque.deleteLast();			// return true
circularDeque.insertFront(4);			// return true
circularDeque.getFront();			// return 4

 

Note:

• All values will be in the range of [0, 1000].
• The number of operations will be in the range of [1, 1000].
• Please do not use the built-in Deque library.

 

 

 

Runtime: 112 ms, faster than 32.91% of Java online submissions for Design Circular Deque.

 

class MyCircularDeque {
  private Deque<Integer> dq = new LinkedList<>();
  private int cap;
  /** Initialize your data structure here. Set the size of the deque to be k. */
  public MyCircularDeque(int k) {
    cap = k;
  }

  /** Adds an item at the front of Deque. Return true if the operation is successful. */
  public boolean insertFront(int value) {
    if(dq.size() == cap) return false;
    dq.offerFirst(value);
    return true;
  }

  /** Adds an item at the rear of Deque. Return true if the operation is successful. */
  public boolean insertLast(int value) {
    if(dq.size() == cap) return false;
    dq.offerLast(value);
    return true;
  }

  /** Deletes an item from the front of Deque. Return true if the operation is successful. */
  public boolean deleteFront() {
    if(dq.size() == 0) return false;
    dq.removeFirst();
    return true;
  }

  /** Deletes an item from the rear of Deque. Return true if the operation is successful. */
  public boolean deleteLast() {
    if(dq.size() == 0) return false;
    dq.removeLast();
    return true;
  }

  /** Get the front item from the deque. */
  public int getFront() {
    if(dq.size() == 0) return -1;
    return dq.peekFirst();
  }

  /** Get the last item from the deque. */
  public int getRear() {
    if(dq.size() == 0) return -1;
    return dq.peekLast();
  }

  /** Checks whether the circular deque is empty or not. */
  public boolean isEmpty() {
    return dq.size() == 0;
  }

  /** Checks whether the circular deque is full or not. */
  public boolean isFull() {
    return dq.size() == cap;
  }
}