队列加分项：杨辉三角

要求：

• 1 用实现循环队列
• 2 参考PPT用循环队列打印杨辉三角
• 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

分析过程：

• 杨辉三角的构造，其两腰上的数都唯一，其余每个数都为其上方左右两数之和
• 为计算方便首尾加0
• 具体思路和老师的PPT大概一致（附图）
  

代码一：CircularArrayQueue

public class CircularArrayQueue<T> implements Queue<T>
{
    private final int DEFAULT_CAPACITY = 10000;
    private int front, rear, size;
    private T[] queue;
    //-----------------------------------------------------------------
// Creates an empty queue using the default capacity.
//-----------------------------------------------------------------
    public CircularArrayQueue()
    {
        front = rear = size = 0;
        queue = (T[]) (new Object[DEFAULT_CAPACITY]);
    }
    //-----------------------------------------------------------------
// Adds the specified element to the rear of this queue, expanding
// the capacity of the queue array if necessary.
//-----------------------------------------------------------------
    public void enqueue (T element)
    {
        if (size == queue.length)
            expandCapacity();
        queue[rear] = element;
        rear = (rear+1) % queue.length;
        size++;
    }
    public void expandCapacity()
    {
        T[] larger = (T[])(new Object[queue.length*2]);
        for (int index = 0; index < size; index++)
            larger[index] = queue[(front+index) % queue.length];
        front = 0;
        rear = size;
        queue = larger;
    }

    @Override
    public T dequeue()
    {
        if (size == 0)
            throw new EmptyCollectionException("queue");
        T d = queue[front];
        queue[front] = null;
        front = (front+1)%queue.length;
        size--;
        return d;
    }

    @Override
    public T first() {
        return queue[front];
    }

    @Override
    public boolean isEmpty() {
        boolean course = false;
        if(size ==0){
            course = true;
        }
        return course;
    }

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



    @Override
    public String toString(){
        String result = "";
        int scan = 0;

        while(scan < size)
        {
            if(queue[scan]!=null)
            {
                result += queue[scan].toString()+"
";
            }
            scan++;
        }
        return result;
    }
}

代码二：杨辉三角

import java.util.Scanner;
public class YangHuiSanJiao {

    public static void main(String[] args) {
        System.out.println("输入行数：");
        Scanner sca = new Scanner(System.in);
        CircularArrayQueue qu = new CircularArrayQueue();
        qu.enqueue(0);
        qu.enqueue(1);
        int b = sca.nextInt();
        int z=0,j= 0,d;
        System.out.println(1);
        for (int a = 1;a<= b - 1; a++){
            qu.enqueue(0);
            for (int ai =1;ai< qu.size();ai++){
                z= (int) qu.first();
                qu.dequeue();
                j = (int) qu.first();
                d = z+j;
                qu.enqueue(d);
                System.out.print(d + " ");
            }
            System.out.println();
        }
    }



}

单步跟踪结果截图：