DesignCircularQueue.java

class MyCircularQueue {
    int F;
    int R;
    boolean noElPresent;
    int[] cqueue = null;

    public MyCircularQueue(int k) {
        this.cqueue = new int[k];
        this.noElPresent  = true;
        this.F = 0;
        this.R = 0;

    }
    //O(1)
    public boolean enQueue(int value) {
        if(this.isFull()){
            return false;
        } else{
            this.noElPresent = false;
            cqueue[R]  =value;
            R = (R+1) % cqueue.length;
            return true;
        }
    }
    // O(1)
    public boolean deQueue() {
        if(this.isEmpty()){
            return false;
        } else{
            F = (F+1) % cqueue.length;
            if(R==F){
                this.noElPresent = true;
            }
            return true;
        }
    }

    // O(1)
    public int Front() {
        if(this.isEmpty()){
            return -1;
        } else{
            return cqueue[F];
        }
    }

    // O(1)
    public int Rear() {
        if(this.isEmpty()){
            return -1;
        } else{
            if(R == 0){
                return cqueue[cqueue.length-1];
            } else{
                return cqueue[R-1];
            }
        }
    }

    // O(1)
    public boolean isEmpty() {
        return this.noElPresent;
    }

    // O(1)
    public boolean isFull() {
        return F==R && !this.isEmpty();// F ==R && !this.noElPresent
    }
}

/**
 * Your MyCircularQueue object will be instantiated and called as such:
 * MyCircularQueue obj = new MyCircularQueue(k);
 * boolean param_1 = obj.enQueue(value);
 * boolean param_2 = obj.deQueue();
 * int param_3 = obj.Front();
 * int param_4 = obj.Rear();
 * boolean param_5 = obj.isEmpty();
 * boolean param_6 = obj.isFull();
 */