Java study notes Day16: stacks and queues

Stack (last out)

Stack method:

• E push (E item) push
• E pop () pop
• E peek () View the top element
• Whether boolean empty () determines stack is empty

Order to achieve stack table

public class MyStack {
	private int[] array = new int[100];
	array[size++] = v;
	public void push(int v) {
		array[size++] = v;
	}
	public int pop() {
		return array[--size];
	}
	public int peek() {
		return array[size - 1];
	}
	public boolean isEmpty() {
		return size == 0;
	}
	public int size() {
		return size;
	}
}

Queue (last out)

Queue method

Error Handling	Throw an exception	Returns the special value
Into the queue	add(e)	offer(e)
The queue	remove()	poll()
Team first element	element()	peek()

Circular queue

Achieve circular queue

class MyCircularQueue {
    int[] a;
    int front;
    int rear;
    int size;
    /** Initialize your data structure here. Set the size of the queue to be k. */
    public MyCircularQueue(int k) {
        a=new int[k+1];
       front=rear=0;
       size=k+1;
    }
    
    /** Insert an element into the circular queue. Return true if the operation is successful. */
    public boolean enQueue(int value) {
        if(isFull()){
            return false;
        }
        a[rear]=value;
        rear=(rear+1)%size;
        return true;
    }
    
    /** Delete an element from the circular queue. Return true if the operation is successful. */
    public boolean deQueue() {
        if(isEmpty()){
            return false;
        }
        front=(front+1)%size;
        return true;
    }
    
    /** Get the front item from the queue. */
    public int Front() {
        if(isEmpty()){
            return -1;
        }
       return a[front]; 
    }
    
    /** Get the last item from the queue. */
    public int Rear() {
        if(isEmpty()){
            return -1;
        }
        return a[(rear-1+size)%size];
    }
    
    /** Checks whether the circular queue is empty or not. */
    public boolean isEmpty() {
        if(front==rear){
            return true;
        }
        return false;
    }
    
    /** Checks whether the circular queue is full or not. */
    public boolean isFull() {
        if((rear+1)%size==front){
            return true;
        }
        return false;
    }
}