数据结构与算法__07--前序、中序、后序线索化二叉树，前序、中序、后序线索化二叉树遍历（Java语言版本）

1 前序

//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();
 
    }
}

2 后序

2.1 为节点添加父节点

2.1.1 节点中创建方法

//前序遍历添加父节点
public void preOrderAddPar() {
    while (this.getLeft() != null) {
        this.getLeft().setParent(this);
        break;
    }
    while (this.getRight() != null) {
        this.getRight().setParent(this);
        break;
    }
 
    if (this.getLeft() != null) {//2.向左遍历
        this.getLeft().preOrderAddPar();
    }
    if (this.getRight() != null) {//3.向右遍历
        this.getRight().preOrderAddPar();
    }
}

2.1.2 二叉树中创建方法

//前序遍历添加父节点
public void preOrderAddPar() {
    if (this.root != null) {
        this.root.preOrderAddPar();
    } else {
        System.out.println("二叉树为空");
    }
}

2.2 后序线索化及遍历

//后序线索化二叉树   8,10,3,14,6,1
public void threadedPostNode(HeroNode node) {
    if (node == null) {
        return;
    }
    //线索化左子树
    threadedPostNode(node.getLeft());
 
    //线索化右子树
    threadedPostNode(node.getRight());
    //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;
}
 
//后序遍历线索化二叉树的方法
public void threadedPostList() {//8,10,3,14,6,1
    HeroNode node = root;
    while(node != null && node.getLeftType()!=1) {
        node = node.getLeft();
    }
 
    HeroNode pre = null;
    while(node != null) {
        //右节点是线索
        if (node.getRightType() == 1) {
            System.out.println(node);
            pre = node;
            node = node.getRight();
 
        } else {
            //如果上个处理的节点是当前节点的右节点
            if (node.getRight() == pre) {
                System.out.println(node);
                if (node == root) {
                    return;
                }
 
                pre = node;
                node = node.getParent();
 
            } else {    //如果从左节点的进入则找到有子树的最左节点
                node = node.getRight();
                while (node != null && node.getLeftType() !=1) {
                    node = node.getLeft();
                }
            }
        }
    }
}

3 中序

//重载中序线索化二叉树
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());
}

4 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);
 
        
        ThreadedBinaryTree threadedBinaryTree = new ThreadedBinaryTree();
        threadedBinaryTree.setRoot(root);
 
        //为节点遍历添加父节点
        threadedBinaryTree.preOrderAddPar();
        
//        中序  8, 3, 10, 1, 14, 6
/*        threadedBinaryTree.threadedNode();
        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();*/
 
        //后序8,10,3,14,6,1
        threadedBinaryTree.threadedPostNode(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.threadedPostList();
 
    }
}
 
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 HeroNode parent;//父节点
    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 HeroNode getParent() {
        return parent;
    }
 
    public void setParent(HeroNode parent) {
        this.parent = parent;
    }
 
    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;
    }
 
    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 + '\'' +
                '}';
    }
 
    //前序遍历添加父节点
    public void preOrderAddPar() {
        while (this.getLeft() != null) {
            this.getLeft().setParent(this);
            break;
        }
        while (this.getRight() != null) {
            this.getRight().setParent(this);
            break;
        }
 
        if (this.getLeft() != null) {//2.向左遍历
            this.getLeft().preOrderAddPar();
        }
        if (this.getRight() != null) {//3.向右遍历
            this.getRight().preOrderAddPar();
        }
    }
 
    //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 HeroNode getRoot() {
        return root;
    }
 
    public void setRoot(HeroNode root) {
        this.root = root;
    }
 
    //重载中序线索化二叉树
    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());
    }
 
    //后序线索化二叉树   8,10,3,14,6,1
    public void threadedPostNode(HeroNode node) {
        if (node == null) {
            return;
        }
        //线索化左子树
        threadedPostNode(node.getLeft());
 
        //线索化右子树
        threadedPostNode(node.getRight());
        //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;
    }
 
    //后序遍历线索化二叉树的方法
    public void threadedPostList() {//8,10,3,14,6,1
        HeroNode node = root;
        while(node != null && node.getLeftType()!=1) {
            node = node.getLeft();
        }
 
        HeroNode preNode = null;
        while(node != null) {
            //右节点是线索
            if (node.getRightType() == 1) {
                System.out.println(node);
                preNode = node;
                node = node.getRight();
 
            } else {
                //如果上个处理的节点是当前节点的右节点
                if (node.getRight() == preNode) {
                    System.out.println(node);
                    if (node == root) {
                        return;
                    }
 
                    preNode = node;
                    node = node.getParent();
 
                } else {    //如果从左节点的进入则找到有子树的最左节点
                    node = node.getRight();
                    while (node != null && node.getLeftType() !=1) {
                        node = node.getLeft();
                    }
                }
            }
        }
    }
 
    //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();
 
        }
    }
 
    //前序遍历添加父节点
    public void preOrderAddPar() {
        if (this.root != null) {
            this.root.preOrderAddPar();
        } else {
            System.out.println("二叉树为空");
        }
    }
    //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");
        }
    }
}