队列课下作业

队列课下作业

作业要求：

1. 补充课上没有完成的作业
2. 参考15.3节，用自己完成的队列（链队，循环数组队列）实现模拟票务柜台排队功能
3. 用JDB或IDEA单步跟踪排队情况，画出队列变化图，包含自己的学号信息
4. 把代码推送到代码托管平台
5. 把完成过程写一篇博客：重点是单步跟踪过程和遇到的问题及解决过程
6. 提交博客链接

代码实现：

链队实现：

import exception.*;

public class MyLinkedQueue<T> implements QueueADT<T>
{
    private int total;
    private LinearNode<T> front, rear;

    public MyLinkedQueue()
    {
        total = 0;
        front = null;
        rear = null;
    }

    public void enqueue (T element)
    {
        LinearNode<T> e = new LinearNode<>(element);
        if (!isEmpty()){
            rear.setNext(e);
        }else {
            front = e;
        }
        total += 1;
        rear = e;
    }

    public T dequeue() throws EmptyCollectionException
    {
        if (isEmpty())throw new EmptyCollectionException("LinearQueue");
        LinearNode<T> e = front;
        front = front.getNext();
        total -= 1;
        if (isEmpty())rear = null;
        return e.getElement();
    }


    public T first() throws EmptyCollectionException
    {
        if (isEmpty())throw new EmptyCollectionException("LinearQueue");
        return front.getElement();
    }


    public boolean isEmpty()
    {
        return total==0?true:false;
    }

    public int size()
    {
        return total;
    }

    public String toString()
    {
        String rlt = "REAR OF QUEUE\n";
        LinearNode<T> currentNode = rear;
        while (currentNode !=null){
            rlt += currentNode.getElement().toString();
            rlt += "\n";
            currentNode = rear.getNext();
        }
        return rlt+"FRONT OF QUEUE";
    }
}

数组队列实现：

import exception.*;
public class MyCircularArrayQueue<T> implements QueueADT<T> {
    private final int DEFAULT_CAPACITY = 10;
    private int front, rear, count;
    private T[] queue;


    public MyCircularArrayQueue() {
        front = rear = count = 0;
        queue = (T[]) (new Object[DEFAULT_CAPACITY]);
    }

    public void enqueue(T element) {
        if (count == queue.length)
            expandCapacity();
        queue[rear] = element;
        rear = (rear + 1) % queue.length;
        count += 1;
    }

    @Override
    public T dequeue() throws EmptyCollectionException {
        if (isEmpty()) throw new EmptyCollectionException("CircularQueue");
        T rlt = queue[front];
        front = (front + 1) % queue.length;
        count -= 1;
        return rlt;
    }

    @Override
    public int size() {
        return count;
    }

    @Override
    public boolean isEmpty() {
        return count==0?true:false;
    }

    @Override
    public T first() throws EmptyCollectionException {
        if (isEmpty()) throw new EmptyCollectionException("CircularQueue");
        return queue[front];
    }

    public void expandCapacity() {
        T[] larger = (T[]) (new Object[queue.length * 2]);
        for (int index = 0; index < count; index++)
            larger[index] = queue[(front + index) % queue.length];
        front = 0;
        rear = count;
        queue = larger;
    }
}

模拟柜台实现：

import java.util.ArrayList;

public class MockBooking {
    final static int PROCESS = 120;
    final static int MAX_CASHIERS = 10;
    final static int NUM_CUSTOMERS = 100;
    public static void main(String[] args) {
        Customer customer;
        MyCircularArrayQueue<Customer> customerQueue = new MyCircularArrayQueue<>();
        int[] cashierTime = new int[MAX_CASHIERS];
        int totalTime, averageTime, departs;
        for (int cashiers=0; cashiers < MAX_CASHIERS; cashiers++) {
            for (int count=0; count < cashiers; count++)
                cashierTime[count] = 0;
            for (int count=1; count <= NUM_CUSTOMERS; count++)
                customerQueue.enqueue(new Customer(count*15));
            totalTime = 0;
            while (!(customerQueue.isEmpty()))
            {
                for (int count=0; count <= cashiers; count++)
                {
                    if (!(customerQueue.isEmpty()))
                    {customer = customerQueue.dequeue();
                        if (customer.getArrivalTime() > cashierTime[count])
                            departs = customer.getArrivalTime() + PROCESS;
                        else
                            departs = cashierTime[count] + PROCESS;
                        customer.setDepartureTime (departs);
                        cashierTime[count] = departs;
                        totalTime += customer.totalTime();
                    }
                }
            }
            averageTime = totalTime / NUM_CUSTOMERS;
            System.out.println ("Number of cashiers: " + (cashiers+1));
            System.out.println ("Average time: " + averageTime + "\n");
        }
    }
}

单步跟踪

队列变化图：