双端队列

4.2 根据本章里对双端队列的讨论编写一个Deque类，它应该包括insertLeft()、insertRight()、removeLeft()、removeRight()、 isEmpty()、isFull()方法。要求像队列那样支持在数据末端的回绕。

public class DuQueue {
    private int maxSize;
    private long[] queArray;
    private int front;
    private int rear;
    private int nItems;

    public DuQueue(int s){
        maxSize=s;
        queArray = new long[maxSize];
        front=0;
        rear=-1;
        nItems=0;
    }

    public void insertLeft(long value){
        if(front==0){
            front=maxSize;
        }
        queArray[--front]=value;
        nItems++;
    }

    public void insertRight(long value){
        if(rear==maxSize-1){
            rear=-1;
        }
        queArray[++rear]=value;
        nItems++;
    }

    public long removeLeft(){
        long temp = queArray[front++];
        if(front==maxSize){
            front=0;
        }
        nItems--;
        return temp;
    }

    public long removeRight(){
        long temp = queArray[rear--];
        if(rear==-1){
            rear=maxSize-1;
        }
        nItems--;
        return temp;
    }

    public long peekLeft(){
        return queArray[front];
    }

    public long peekRight(){
        return queArray[rear];
    }

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

    public boolean isFull(){
        return (nItems==maxSize);
    }

    public int size(){
        return nItems;
    }

    public void display(){
        System.out.print("队列为： ");
        if(nItems==0){
            System.out.println("空。 ");
            return;
        }
        if(rear>=front){
            for(int i =front;i<=rear;i++){
                System.out.print(queArray[i]+" ");
            }
        }
        else{
            for(int i =front;i<maxSize;i++){
                System.out.print(queArray[i]+" ");
            }
            for(int i =0;i<=rear;i++){
                System.out.print(queArray[i]+" ");
            }
        }
        System.out.println();
    }

}

public class DuQueueApp {

    /** * @param args */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        DuQueue theQueue = new DuQueue(5);
        theQueue.insertRight(10);
        theQueue.insertRight(20);
        theQueue.insertRight(30);
        theQueue.insertRight(40);
        theQueue.display();
        System.out.println("移除"+theQueue.removeLeft());
        System.out.println("移除"+theQueue.removeLeft());
        System.out.println("移除"+theQueue.removeLeft());
        theQueue.display();
        theQueue.insertLeft(50);
        theQueue.insertLeft(60);
        theQueue.insertLeft(70);
        theQueue.insertLeft(80);
        theQueue.display();
        theQueue.removeRight();
        theQueue.removeRight();
        theQueue.removeRight();
        theQueue.display();

    }

}