LeetCode 641. Design Circular Deque

Question

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.

https://leetcode.com/problems/design-circular-deque/

class MyCircularDeque {
    int[] q;
    int front = 0, rear = -1, size = 0, capacity;
    public MyCircularDeque(int k) {
        q = new int[k];
        capacity = k;
    }
    
    public boolean insertFront(int value) {
        if(isFull()) return false;
        if(--front < 0) front +=capacity;
        q[front] = value;
        size++;
        if(size == 1) rear = front;
        return true;
    }
    
    public boolean insertLast(int value) {
        if (isFull()) return false;
        rear = (rear + 1) % capacity;
        q[rear] = value;
        size++;
        return true; 
    }
    
    public boolean deleteFront() {
        if (isEmpty()) return false;
        front = (front + 1) % capacity;
        size--;
        return true;
    }
    
    public boolean deleteLast() {
        if(isEmpty()) return false;
        if(--rear < 0) rear += capacity;
        size--;
        return true;
    }
    
    public int getFront() {
        return isEmpty() ? -1 : q[front];
    }
    
    public int getRear() {
        return isEmpty() ? -1 : q[rear];
    }
    
    public boolean isEmpty() {
        return size == 0;
    }
    
    public boolean isFull() {
        return size == capacity;
    }
}

Time Complexity:

MyCircularDeque, O(1). insertFront, O(1). insertLast, O(1). deleteFront, O(1). deleteLast, O(1). getFront, O(1). getRear, O(1). isEmpty(): O(1), isFull(): O(1).

Space: O(k).