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;
    }
}

原文地址：https://www.cnblogs.com/train99999/p/11107839.html