[LeetCode] Problem 641 - Design Circular Deque

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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

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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.

Code

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private int[] queue;
private int front;
private int rear;
private int size;

public MyCircularDeque(int k) {
    queue = new int[k];
    front = 0;
    rear = -1;
    size = 0;
}

public boolean insertFront(int value) {
    if (!isFull()) {
        if (isEmpty()) {
            front = 0;
            rear = 0;
        }
        else
            front = (front - 1 + queue.length) % queue.length;

        queue[front] = value;
        size++;
        return true;
    }

    return false;
}

public boolean insertLast(int value) {
    if (!isFull()) {
        rear = (++rear) % queue.length;
        queue[rear] = value;
        size++;
        return true;
    }

    return false;
}

public boolean deleteFront() {
    if (!isEmpty()) {
        front = (++front) % queue.length;
        size--;
        return true;
    }

    return false;
}

public boolean deleteLast() {
    if (!isEmpty()) {
        rear = (rear - 1 + queue.length) % queue.length;
        size--;
        return true;
    }

    return false;
}

public int getFront() {
    if (isEmpty())
        return -1;

    return queue[front];
}

public int getRear() {
    if (isEmpty())
        return -1;

    return queue[rear];
}

public boolean isEmpty() {
    return size == 0;
}

public boolean isFull() {
    return size == queue.length;
}