链表学习习习

第3章链表

链表是有序的列表,但是它在内存中的存储不一定是连续的

链表是以节点的方法来存储的
每个节点包含date域,next域:指向下一个节点
链表的各个节点不一定是连续存储
链表分为头节点的链表和没有头节点的链表根据实际需求来定

内存实际结构

3.1单链表

简单单链表实现

public class Main {
    public static void main(String[] args) {
        Hero hero1 = new Hero("张三", 20);
        Hero hero2 = new Hero("李四", 30);
        Hero hero3 = new Hero("王五", 40);
        SingleLinkedList list = new SingleLinkedList();
        list.addHero(hero1);
        list.addHero(hero2);
        list.addHero(hero3);
        list.print();
    }
}
class Hero{
    private String name;
    private int age;
     Hero next;
    public Hero(String name, int age) {
        this.name = name;
        this.age = age;
    }

    @Override
    public String toString() {
        return "Hero{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}
class SingleLinkedList{
    private Hero head=new Hero("",0);
    public void addHero(Hero hero){//添加英雄
        Hero temp = head;
        if(temp.next == null){
            temp.next = hero;
            return;
        }
        while(temp.next!=null){
            temp = temp.next;
        }
        temp.next = hero;
    }
    public void print(){//遍历英雄
        Hero temp = head;
        while(temp.next!=null){
            System.out.println(temp.next.toString());
            temp = temp.next;
        }
    }
}

3.2按顺序插入和删除排序单链表

public class Main {
    public static void main(String[] args) {
        Hero hero1 = new Hero("张三", 30);
        Hero hero2 = new Hero("李四", 20);
        Hero hero3 = new Hero("王五", 10);
        SingleLinkedList list = new SingleLinkedList();
        list.addHero(hero1);
        list.addHero(hero2);
        list.addHero(hero3);
        list.print();
        System.out.println("==============");
        list.deleteHero(hero2);
        list.print();
    }
}
class Hero{
    private String name;
    private int age;
     Hero next;
    public Hero(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Hero getNext() {
        return next;
    }

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

    @Override
    public String toString() {
        return "Hero{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}
class SingleLinkedList{
    private Hero head=new Hero("",0);
    public void addHero(Hero hero){//添加英雄
        Hero temp = head;
        if(temp.next == null){
            temp.next = hero;
            return;
        }
        while(temp.next!=null){
            if(temp.next.getAge()>hero.getAge()){
                break;
            }
           temp = temp.next;
        }
        hero.next = temp.next;
        temp.next=hero;
    }
    public void deleteHero(Hero hero){//删除英雄
        Hero temp = head;
        while(temp.next!=null){
            if(temp.next.getAge()==hero.getAge()){
                temp.next = temp.next.next;
                break;
            }
            temp = temp.next;
        }
    }
    public void print(){//遍历英雄
        Hero temp = head;
        while(temp.next!=null){
            System.out.println(temp.next.toString());
            temp = temp.next;
        }
    }
}

3.3企业面试题实现单链表一些功能

有链表数据反转和链表长度和链表特定索引查询

public class Main {
    public static void main(String[] args) {
        Hero hero1 = new Hero("张三", 30);
        Hero hero2 = new Hero("李四", 20);
        Hero hero3 = new Hero("王五", 10);
        SingleLinkedList list = new SingleLinkedList();
        list.addHero(hero1);
        list.addHero(hero2);
        list.addHero(hero3);
        list.print();
        System.out.println("==============");
        reserve(list.head);
        list.print();



    }
    public static Hero reserve(Hero heroHead) {
       Hero endHero = new Hero("",0);
       Hero tempHead = heroHead.next;//临时结点存放原链表第一个节点
       Hero next=null;//用来存放原链表第二个节点
       while (tempHead != null) {
           next=tempHead.next;//存放原链表第二个节点
           tempHead.next=endHero.next;//将第二个节点指向最终链表的第一个节点
            endHero.next=tempHead;//将最终节点指向当前第一个节点

            tempHead=next;//将节点改成第二个节点
       }
       return heroHead.next=endHero.next;
    }
}
class Hero{
    private String name;
    private int age;
     Hero next;
    public Hero(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Hero getNext() {
        return next;
    }

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

    @Override
    public String toString() {
        return "Hero{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}
class SingleLinkedList{
     Hero head=new Hero("",0);

    public void addHero(Hero hero){//添加英雄
        Hero temp = head;
        if(temp.next == null){
            temp.next = hero;
            return;
        }
        while(temp.next!=null){
            if(temp.next.getAge()>hero.getAge()){
                break;
            }
           temp = temp.next;
        }
        hero.next = temp.next;
        temp.next=hero;
    }
    public void deleteHero(Hero hero){//删除英雄
        Hero temp = head;
        while(temp.next!=null){
            if(temp.next.getAge()==hero.getAge()){
                temp.next = temp.next.next;
                break;
            }
            temp = temp.next;
        }
    }
    public void print(){//遍历英雄
        Hero temp = head;
        while(temp.next!=null){
            System.out.println(temp.next.toString());
            temp = temp.next;
        }
    }
    public Hero getHero(int index){//查看倒数第几个英雄
        Hero temp = head;
        for(int i=0;i<this.getLength()-index;i++){
            temp = temp.next;
        }
        return temp;
    }
    public int getLength(){//查看链表长度
        Hero temp = head;
        int length = 0;
        while(temp.next!=null){
            length++;
            temp = temp.next;
        }
        return length;
    }
}

4.4单链表实现逆序打印

思路:

先将单链表进行反转操作,然后再遍历即可,这样做的问题会破坏原来的单链表结构,不建议
可以利用栈这个数据结构,将各个节点压入到栈中然后利用先进后出的特点,就实现了逆序打印的效果

演示

public static void reservePrint(HeroNode head){
        if(head.next==null){
            return ;
        }
        HeroNode cur=head.next;
        Stack<HeroNode> heroNodes = new Stack<>();
        while (cur!=null){
            heroNodes.push(cur);//压入栈
            cur=cur.next;
        }
        while (heroNodes.size()>0){
            System.out.println(heroNodes.pop());//弹出栈
        }
    }

4.5双向链表实现及功能

遍历方式和单链表一样,但是可以从后向前
添加 temp.next=newHeroNode newHeroNode.pre=temp;
修改思路和单聊表一样
删除
1. 因为是双向链表,因此,我们可以实现自我删除某个节点
2. 直接找到要删除的节点比如temp
3. temo.pre.next=temp.next
4. temp.next.pre=temp.pre

import java.util.Queue;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        HeroNode h1 = new HeroNode(1, "小明");
        HeroNode h2 = new HeroNode(2, "小红");
        HeroNode h3 = new HeroNode(3, "小蓝");
        HeroNode h4 = new HeroNode(4, "小绿");
        DoubleLinkedList d = new DoubleLinkedList();
        d.add(h1);
        d.add(h2);
        d.list();
        System.out.println("==========");
        d.unList();
    }
}
//双向链表存放
class DoubleLinkedList{
        private HeroNode tail=new HeroNode(0,"");
      private HeroNode head= new HeroNode(0,"");
      public void add(HeroNode h){//添加元素
          if(head.next==null){
              head.next=h;
              tail=h;
              return;
          }
          HeroNode temp=head;
          while (temp.next!=null){
              if(h.a<=temp.next.a){
                  temp.next.pre=h;
                  h.next=temp.next;
                  temp.next=h;
                  h.pre=temp;
                return;
              }
              temp=temp.next;
          }
          temp.next=h;
          h.pre=temp;
          tail=h;
      }
      public void upDate(int a){
          Scanner sc = new Scanner(System.in);
          HeroNode temp=head;
          while (temp.next!=null){
              if(temp.next.a==a){
                  System.out.println("请输入要改成的序号和名字");
                  temp.next.a=sc.nextInt();
                  temp.next.name=sc.nextLine();
                  return;
              }
          }
          System.out.println("没有这个年龄的值");
      }
      public void unList(){
          HeroNode temp=tail;
          while (temp!=null){
              System.out.println(temp.toString());
              temp=temp.pre;
          }
      }
      public void list(){
        HeroNode temp=head;
        while (temp.next!=null){
            System.out.println(temp.next.toString());
            temp=temp.next;
        }
      }
}
class HeroNode{
    public int a;
    public String name;
    public HeroNode next;
    public HeroNode pre;

    public HeroNode(int a, String name){
        this.a=a;
        this.name=name;
    }

    @Override
    public String toString() {
        return (a+"     "+name );
    }
}

4.6双向链表约瑟夫问题

import java.util.Stack;

public class Main {
    public static void main(String[] args) {
        Josepfu j = new Josepfu();
        j.addBoy(5);
        j.showBoy();
    }
}
class Boy{
    private int age;
    private Boy next;
    public Boy(int age) {
        this.age = age;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Boy getNext() {
        return next;
    }

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

    private Boy first=null;
    public void addBoy(int num){// 添加数据
        Boy curBoy=null;
        for (int i = 1; i <=num ; i++) {
            Boy boy = new Boy(i);
            if(i>1){
                curBoy.setNext(boy);
                boy.setNext(first);
            }else {
                first=boy;
                boy.setNext(first);
            }
            curBoy=boy;
        }
    }
    public void showBoy(){//遍历孩子年龄
        Boy curBoy=first;
        while (true){
            System.out.println(curBoy.getAge());
            if(curBoy.getNext()==first){
                break;
            }
            curBoy=curBoy.getNext();
        }
    }
}

import java.util.Stack;

public class Main {
    public static void main(String[] args) {
        Josepfu j = new Josepfu();
        j.addBoy(5);
        j.showBoy();
    }
}
class Boy{
    private int age;
    private Boy next;
    public Boy(int age) {
        this.age = age;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Boy getNext() {
        return next;
    }

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

    private Boy first=null;
    public void addBoy(int num){// 添加数据
        Boy curBoy=null;
        for (int i = 1; i <=num ; i++) {
            Boy boy = new Boy(i);
            if(i>1){
                curBoy.setNext(boy);
                boy.setNext(first);
            }else {
                first=boy;
                boy.setNext(first);
            }
            curBoy=boy;
        }
    }
    public void showBoy(){//遍历孩子年龄
        Boy curBoy=first;
        while (true){
            System.out.println(curBoy.getAge());
            if(curBoy.getNext()==first){
                break;
            }
            curBoy=curBoy.getNext();
        }
    }
    public void countBoy(int startNo,int countNum,int nums){//从第几个人开始  报几个数 一共多少个人
        if(startNo<1||first==null||countNum>nums){
            System.out.println("数据不符合");
            return;
        }
        Boy helper=first;
        while (true){
            if(helper.getNext()==first){
                break;
            }
            helper=helper.getNext();
        }
        while (true){
            if(helper.getNext()==first){
                break;
            }
            helper=helper.getNext();
        }
        for (int i = 1; i <startNo ; i++) {//报数前,先让first和helper移动k-1次
            first=first.getNext();
            helper=helper.getNext();
        }
        while (first.getNext()!=first){//当小孩报数时让first和helper同时移动
            for (int i = 0; i <countNum-1 ; i++) {
                first=first.getNext();
                helper=helper.getNext();
            }
            System.out.println("出圈元素为"+first.getAge());
            first=first.getNext();
            helper.setNext(first);
        }
        System.out.println("最后留下的小孩"+first.getAge());
        
    }
}

链表学习习习

第3章 链表

3.1单链表

3.2按顺序插入和删除排序单链表

3.3企业面试题实现单链表一些功能

4.4单链表实现逆序打印

4.5双向链表实现及功能

4.6双向链表约瑟夫问题

悦读

第3章链表