数据结构与算法__03--二叉树前序线索化与前序线索化遍历（Java语言版）

Posted 2022-12-13

(目录)

1 前序线索化与前序线索化遍历

1.1 前序线索化二叉树

public void threadedPreNode(HeroNode node) 
    if (node == null) 
        return;
    
    //线索化当前节点
    if (node.getLeft() == null) 
        node.setLeft(pre);
        node.setLeftType(1);
    
    if (pre != null && pre.getRight() == null) 
        pre.setRight(node);
        pre.setRightType(1);
    
    pre = node;
    //线索化左子树
    if (node.getLeftType() != 1) 
        threadedPreNode(node.getLeft());
    
    //线索化右子树
    if (node.getRightType() != 1) 
        threadedPreNode(node.getRight());
    
 

1.2 前序线索化遍历

public void threadedPreList() 
    //定义一个变量，存储当前遍历的结点，从root开始
    HeroNode node = root;
    while (node != null) 
        //打印当前这个结点
        System.out.println(node);
        while (node.getLeftType() == 0) 
            node = node.getLeft();
            System.out.println(node);
        
        //如果当前结点的右指针指向的是后继结点,就一直输出
        while (node.getRightType() == 1) 
            //获取到当前结点的后继结点
            node = node.getRight();
            System.out.println(node);
        
        //替换这个遍历的结点
        node = node.getRight();
 
    

2 完整代码

package edu.seu.demo10tree.demothreadedbinarytree;
 
public class Demo01ThreadedBinaryTree 
    public static void main(String[] args) 
        //测试一把中序线索二叉树的功能
        HeroNode root = new HeroNode(1, "tom");
        HeroNode node2 = new HeroNode(3, "jack");
        HeroNode node3 = new HeroNode(6, "smith");
        HeroNode node4 = new HeroNode(8, "mary");
        HeroNode node5 = new HeroNode(10, "king");
        HeroNode node6 = new HeroNode(14, "dim");
 
        //二叉树，后面我们要递归创建, 现在简单处理使用手动创建
        root.setLeft(node2);
        root.setRight(node3);
        node2.setLeft(node4);
        node2.setRight(node5);
        node3.setLeft(node6);
 
        //测试中序线索化  8, 3, 10, 1, 14, 6
        ThreadedBinaryTree threadedBinaryTree = new ThreadedBinaryTree();
        threadedBinaryTree.setRoot(root);
 
//        threadedBinaryTree.threadedNode();
//        中序  8, 3, 10, 1, 14, 6
//        HeroNode leftNode = node5.getLeft();
//        HeroNode rightNode = node5.getRight();
//        System.out.println("10号结点的前驱结点是="  + leftNode); //3
//        System.out.println("10号结点的后继结点是="  + rightNode); //1
 
//        System.out.println("使用线索化的方式遍历 线索化二叉树");
//        threadedBinaryTree.threadedList();
 
//        前序 1,3,8,10,6,14
        threadedBinaryTree.threadedPreNode(root);
        HeroNode leftNode = node5.getLeft();
        HeroNode rightNode = node5.getRight();
        System.out.println("10号结点的前驱结点是=" + leftNode);
        System.out.println("10号结点的后继结点是=" + rightNode);
 
        System.out.println("使用线索化的方式遍历 线索化二叉树");
        threadedBinaryTree.threadedPreList();
 
    

 
class HeroNode 
    private int no;//英雄编号
    private String name;//姓名
    private HeroNode left;//左子节点
    private HeroNode right;//右子节点
    private int rightType;//表示右子节点：指针：0，后继：1
    private int leftType;//表示左子节点：指针：0  前驱：1
 
    public int getRightType() 
        return rightType;
    
 
    public void setRightType(int rightType) 
        this.rightType = rightType;
    
 
    public int getLeftType() 
        return leftType;
    
 
    public void setLeftType(int leftType) 
        this.leftType = leftType;
    
//构造方法
 
    public HeroNode(int no, String name) 
        this.no = no;
        this.name = name;
    
 
    //读取与设置私有变量
    public int getNo() 
        return no;
    
 
    public void setNo(int no) 
        this.no = no;
    
 
    public String getName() 
        return name;
    
 
    public void setName(String name) 
        this.name = name;
    
 
    public HeroNode getLeft() 
        return left;
    
 
    public void setLeft(HeroNode left) 
        this.left = left;
    
 
    public HeroNode getRight() 
        return right;
    
 
    public void setRight(HeroNode right) 
        this.right = right;
    
 
    //打印输出
 
    @Override
    public String toString() 
        return "HeroNode" +
                "no=" + no +
                ", name=" + name + \\ +
                ;
    
 
    //前序遍历
    public void preOrder() 
        System.out.println(this);//1.输出父节点
        if (this.getLeft() != null) //2.向左遍历
            this.getLeft().preOrder();
        
        if (this.getRight() != null) //3.向右遍历
            this.getRight().preOrder();
        
    
 
    //中序遍历
    public void infixOrder() 
        if (this.getLeft() != null) 
            this.getLeft().infixOrder();
        
        System.out.println(this);
        if (this.getRight() != null) //3.向右遍历
            this.getRight().infixOrder();
        
    
 
    //后序遍历
    public void postOrder() 
        if (this.getLeft() != null) 
            this.getLeft().postOrder();
        
        if (this.getRight() != null) //3.向右遍历
            this.getRight().postOrder();
        
        System.out.println(this);
    
 
    //前序遍历查找
    public HeroNode preOrderSearch(int no) 
        System.out.println("前序查找比较次数");
        if (this.getNo() == no) 
            return this;
        
        HeroNode resHero = null;
        if (this.left != null) 
            resHero = this.left.preOrderSearch(no);
        
        if (resHero != null) 
            return resHero;
        
        if (this.right != null) 
            resHero = this.right.preOrderSearch(no);
        
        return resHero;
    
 
    //中序遍历查找
    public HeroNode infixOrderSearch(int no) 
        HeroNode resHero = null;
        if (this.left != null) 
            resHero = this.left.infixOrderSearch(no);
        
        if (resHero != null) 
            return resHero;
        
        System.out.println("中序查找比较次数");
        if (this.getNo() == no) 
            return this;
        
        if (this.right != null) 
            resHero = this.right.infixOrderSearch(no);
        
        return resHero;
    
 
    //后序遍历查找
    public HeroNode postOrderSearch(int no) 
        HeroNode resHero = null;
        if (this.left != null) 
            resHero = this.left.postOrderSearch(no);
        
        if (resHero != null) 
            return resHero;
        
 
        if (this.right != null) 
            resHero = this.right.postOrderSearch(no);
        
        if (resHero != null) 
            return resHero;
        
        System.out.println("后序查找比较次数");
        if (this.getNo() == no) 
            return this;
        
        return resHero;
    
 
    //删除节点
    public void delHeroNode(int no) 
        if (this.left != null && this.left.getNo() == no) 
            this.left = null;
            return;
        
        if (this.right != null && this.right.getNo() == no) 
            this.right = null;
            return;
        
        if (this.left != null) 
            this.left.delHeroNode(no);
        
        if (this.right != null) 
            this.right.delHeroNode(no);
        
    
 

 
class ThreadedBinaryTree 
    private HeroNode root;//根节点
    private HeroNode pre = null;
 
    public ThreadedBinaryTree() 
    
 
    public void threadedNode() 
        threadedNode(root);
    
 
    //中序遍历线索化二叉树的方法
    public void threadedList() 
        //定义一个变量，存储当前遍历的结点，从root开始
        HeroNode node = root;
        while (node != null) 
            //循环的找到leftType == 1的结点，第一个找到就是8结点
            //后面随着遍历而变化,因为当leftType==1时，说明该结点是按照线索化
            //处理后的有效结点
            while (node.getLeftType() == 0) 
                node = node.getLeft();
            
 
            //打印当前这个结点
            System.out.println(node);
            //如果当前结点的右指针指向的是后继结点,就一直输出
            while (node.getRightType() == 1) 
                //获取到当前结点的后继结点
                node = node.getRight();
                System.out.println(node);
            
            //替换这个遍历的结点
            node = node.getRight();
 
        
    
 
    //中序线索化二叉树
    public void threadedNode(HeroNode node) 
        if (node == null) 
            return;
        
        //线索化左子树
        threadedNode(node.getLeft());
        //线索化当前节点
        if (node.getLeft() == null) 
            node.setLeft(pre);
            node.setLeftType(1);
        
        if (pre != null && pre.getRight() == null) 
            pre.setRight(node);
            pre.setRightType(1);
        
        pre = node;
        //线索化右子树
        threadedNode(node.getRight());
    
    //前序线索化二叉树
    public void threadedPreNode(HeroNode node) 
        if (node == null) 
            return;
        
        //线索化当前节点
        if (node.getLeft() == null) 
            node.setLeft(pre);
            node.setLeftType(1);
        
        if (pre != null && pre.getRight() == null) 
            pre.setRight(node);
            pre.setRightType(1);
        
        pre = node;
        //线索化左子树
        if (node.getLeftType() != 1) 
            threadedPreNode(node.getLeft());
        
        //线索化右子树
        if (node.getRightType() != 1) 
            threadedPreNode(node.getRight());
        
 
    
 
    //前序线索化遍历
    public void threadedPreList() 
        //定义一个变量，存储当前遍历的结点，从root开始
        HeroNode node = root;
        while (node != null) 
            //打印当前这个结点
            System.out.println(node);
            while (node.getLeftType() == 0) 
                node = node.getLeft();
                System.out.println(node);
            
            //如果当前结点的右指针指向的是后继结点,就一直输出
            while (node.getRightType() == 1) 
                //获取到当前结点的后继结点
                node = node.getRight();
                System.out.println(node);
            
            //替换这个遍历的结点
            node = node.getRight();
 
        
    
 
    public HeroNode getRoot() 
        return root;
    
 
    public void setRoot(HeroNode root) 
        this.root = root;
    
 
 
    //前序遍历
    public void preOrder() 
        if (this.root != null) 
            this.root.preOrder();
         else 
            System.out.println("二叉树为空");
        
    
 
    //中序遍历
    public void infixOrder() 
        if (this.root != null) 
            this.root.infixOrder();
         else 
            System.out.println("二叉树为空");
        
    
 
    //后序遍历
    public void postOrder() 
        if (this.root != null) 
            this.root.postOrder();
         else 
            System.out.println("二叉树为空");
        
    
 
    //前序遍历查找
    public HeroNode preOrderSearch(int no) 
        if (root != null) 
            return root.preOrderSearch(no);
         else 
            return null;
        
    
 
    //中序遍历查找
    public HeroNode infixOrderSearch(int no) 
        if (root != null) 
            return root.infixOrderSearch(no);
         else 
            return null;
        
    
 
    //后序遍历查找
    public HeroNode postOrderSearch(int no) 
        if (root != null) 
            return this.root.postOrderSearch(no);
         else 
            return null;
        
    
 
    //删除节点
    public void delHeroNode(int no) 
        if (root != null) 
            if (root.getNo() == no) 
                root = null;
             else 
                root.delHeroNode(no);
            
         else 
            System.out.println("二叉树为空");