LeetCode 622. Design Circular Queue

Question

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.

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

class MyCircularQueue {
    int[] q;
    int front, rear, size;
    public MyCircularQueue(int k) {
        front = 0;
        rear = -1;
        q = new int[k];
    }
    
    public boolean enQueue(int value) {
        if(!isFull()){
            rear=(rear + 1) % q.length;
            q[rear] = value;
            size++;
            return true;
        } else return false;
    }
    
    public boolean deQueue() {
        if(!isEmpty()){
            front = (front + 1) % q.length;
            size--;
            return true;
        } else return false;
    }
    
    public int Front() {
        return isEmpty() ? -1 : q[front];
    }
    
    public int Rear() {
        return isEmpty() ? -1 : q[rear];
    }
    
    public boolean isEmpty() {
        return size == 0;
    }
    
    public boolean isFull() {
        return size == q.length;
    }
}

Complexity: O(1)

Space complexity: O(k)