双向链表和环形链表(约瑟夫问题)

双向链表

package linkedlist;

public class DooubleLinkedListDemo {
	public static void main(String[] args) {
		HeroNode2 hero1 = new HeroNode2(1,"宋江","及时雨");
		HeroNode2 hero2 = new HeroNode2(2,"卢俊义","玉麒麟");
		HeroNode2 hero3 = new HeroNode2(3,"吴用","智多星");
		HeroNode2 hero4 = new HeroNode2(4,"林冲","豹子头");
		DoubleLinkeList dll = new DoubleLinkeList();
//		dll.add(hero1);
//		dll.add(hero2);
//		dll.add(hero3);
//		dll.add(hero4);
//		dll.list();
//		HeroNode2 hero5 = new HeroNode2(4,"零充","豹子头");
//		dll.update(hero5);
//		dll.list();
//		dll.del(3);
		dll.addByOrder(hero1);
		dll.addByOrder(hero2);
		dll.list();

	}
}

//创建一个双向链表的类
class DoubleLinkeList{
	//初始化一个头结点
	private HeroNode2 head = new HeroNode2(0,"","");
	public HeroNode2 getHead() {
		return head;
	}
	
	//遍历双向链表的方法
	public void list() {
		if(head.next == null) {
			System.out.println("链表为null");
			return;
		}
		//定义辅助变量来遍历
		HeroNode2 temp = head.next;
		while(true) {
			if(temp == null) {
				break;
			}
			System.out.println(temp);
			temp=temp.next;
		}
		
	}
	
	//添加节点
	public void add(HeroNode2 heroNode) {
		//创建辅助及节点
		HeroNode2 temp = head;
		//找到链表最后的节点
		while(true) {
			if(temp.next == null) {
				break;
			}
			//没有找到，往后移
			temp=temp.next;
		}
		temp.next = heroNode;
		heroNode.pre=temp;
	}
	
	//有序添加
	public void addByOrder(HeroNode2 heroNode) {
		HeroNode2 temp = head;//临时变量
		boolean flag = false;//英雄没有存在就添加
		while(true) {
			if(temp.next == null) {
				break;
			}
			if(temp.next.no>heroNode.no) {
				break;
			}else if(temp.next.no == heroNode.no) {
				flag = true;
				break;
			}
			temp = temp.next;
			
		}
		if(flag) {
			System.out.println("编号已经存在");
		}else {
			temp.next=heroNode;
			heroNode.pre=temp;
		}
		
	}
	
	//修改节点的内容
	public void update(HeroNode2 newHeroNode) {
		if(head.next == null) {
			System.out.println("链表为空");
			return;
		}
		//定义辅助变量
		HeroNode2 temp = head.next;
		boolean flag = false;
		while(true) {
			if(temp == null) {
				break;
			}
			if(temp.no == newHeroNode.no) {
				flag = true;
				break;
			}
			temp = temp.next;
		}
		if(flag) {
			temp.name = newHeroNode.name;
			temp.nickname = newHeroNode.nickname;
		}else {
			System.out.println("没有找到要修改的编号");
		}
	}
	
	//删除节点
	public void del(int no) {
		if(head.next == null) {
			System.out.println("链表为空");
			return;
		}
		HeroNode2 temp = head.next;
		boolean flag = false;
		while(true) {
			if(temp == null) {
				break;
			}
			if(temp.no == no) {
				flag = true;
				break;
			}
			temp = temp.next;
		}
		if(flag) {
			temp.pre.next = temp.next;
			if(temp.next != null ) {
				temp.next.pre = temp.pre;
			}
		}else {
			System.out.println("没有找到要删除的节点");
		}
	}
	
}

//定义HeroNode,每个HeroNode 对象就是一个节点
class HeroNode2{
	
	public int no;
	public String name;
	public String nickname;
	public HeroNode2 next;//指向下一个节点
	public HeroNode2 pre;//指向上一个节点
	
	//构造器
	public HeroNode2(int no, String name ,String nickname) {
		this.no = no;
		this.name = name;
		this.nickname = nickname;
	}

	@Override
	public String toString() {
		return "HeroNode [no=" + no + ", name=" + name + ", nickname=" + nickname + "]";
	}
}

约瑟夫问题

package linkedlist;

public class Josephu {
	public static void main(String[] args) {
		CircleSingleLinkedList csll = new CircleSingleLinkedList();
		csll.addBoy(5);
		csll.showBoy();
		
		csll.countBoy(1, 2, 5);
	}
}

//创建一个环形单向链表
class CircleSingleLinkedList{
	//创建一个first节点，当前没有编号
	private Boy first = null;
	//添加小孩节点，构建成一个环形的链表
	public void addBoy(int nums) {
		//nums 做一个数据校验
		if(nums < 1) {
			System.out.println("nums的值不正确");
			return;
		}
		Boy curBoy = null;//辅助指针,帮助构建环形链表
		//使用for循环创建我们环形链表
		for(int i=1; i<=nums; i++) {
			//根据编号，创建小孩节点
			Boy boy = new Boy(i);
			//如果是第一个小孩
			if(i == 1) {
				first =boy;
				first.setNext(first);//构成环装
				curBoy = first;//让curBoy指向第一个小孩
			}else {
				curBoy.setNext(boy);
				boy.setNext(first);
				curBoy = boy;
			}
		}
	}
	
	//遍历
	public void showBoy() {
		if(first.getNext() == null) {
			System.out.println("链表为空");
			return;
		}
		Boy curBoy = first;
		while(true){
			System.out.println(curBoy.getNo());
			if(curBoy.getNext() == first) {
				break;
			}
			curBoy = curBoy.getNext();
		}
	}
	
	//根据用户输入，计算出小孩的出圈顺序
	//startNo 表示从第几个小孩开始数数
	//countNum 表示数几下
	//nums 表示最初由多少个小孩在圈中
	public void countBoy(int startNo,int countNum,int nums) {
		if(first == null || startNo <1 || startNo>nums) {
			System.out.println("参数输入有误");
			return;
		}
		//创建辅助指针，帮助完成小孩出圈
		Boy helper = first;
		//需求创建一个辅助指针helper,事先应该指向环形链表的最后这个节点
		while(true) {
			if(helper.getNext() == first) {
				break;
			}
			helper = helper.getNext();
		}
		for(int j=0;j<startNo-1;j++) {
			first = first.getNext();
			helper = helper.getNext();
		}
		while(true) {
			if(helper == first) {
				break;
			}
			//让first和helper指针同时移动
			for(int j=0;j<countNum-1;j++) {
				first = first.getNext();
				helper = helper.getNext();
			}
			System.out.println("小孩出圈"+first.getNo());
			first=first.getNext();
			helper.setNext(first);
		}
		System.out.println("最后留在圈中额小孩编号"+first.getNo());
	}
}

class Boy{
	private int no;//编号
	private Boy next;//指向下一个节点
	
	public Boy(int no) {
		this.no = no;
	}

	public int getNo() {
		return no;
	}

	public void setNo(int no) {
		this.no = no;
	}

	public Boy getNext() {
		return next;
	}

	public void setNext(Boy next) {
		this.next = next;
	}
}