二叉树的前、中、后序遍历查找与删除

package com.dai.tree;

import java.net.NoRouteToHostException;

public class BinaryTreeDemo {

    public static void main(String[] args) {
        //先创建一个二叉树
        BinaryTree binaryTree = new BinaryTree();
        //创建需要的节点
        HeroNode root = new HeroNode(1, "宋江");
        HeroNode node2 = new HeroNode(2, "吴用");
        HeroNode node3 = new HeroNode(3, "卢俊义");
        HeroNode node4 = new HeroNode(4, "林冲");
        HeroNode node5 = new HeroNode(5, "关胜");
        binaryTree.setRoot(root);
        //说明，先手动创建，后面再递归创建
        root.setLeft(node2);
        root.setRight(node3);
        node3.setRight(node4);
        node3.setLeft(node5);
        
        System.out.println("前序遍历");
        binaryTree.preOrder();
        System.out.println("中序遍历");
        binaryTree.infixOrder();
        System.out.println("后序遍历");
        binaryTree.postOrder();
        
        HeroNode resNode = binaryTree.preOrderSearch(10);
        System.out.println("前序遍历方式");
        if(resNode != null) {
            System.out.println("找到了，信息为" + resNode);
        }else {
            System.out.println("找不到");
        }
        HeroNode resNode1 = binaryTree.infixOrderSearch(10);
        System.out.println("中序遍历方式");
        if(resNode1 != null) {
            System.out.println("找到了，信息为" + resNode1);
        }else {
            System.out.println("找不到");
        }
        HeroNode resNode2 = binaryTree.postOrderSearch(10);
        System.out.println("中序遍历方式");
        if(resNode2 != null) {
            System.out.println("找到了，信息为" + resNode2);
        }else {
            System.out.println("找不到");
        }
        
        //测试删除节点
        System.out.println("删除前的节点：" );
        binaryTree.preOrder();
        binaryTree.delNode(50);
        System.out.println("删除后的节点：");
        binaryTree.preOrder();
    }
}

//定义BinaryTree 二叉树
class BinaryTree{
    private HeroNode root;
    public void setRoot(HeroNode root) {
        this.root = root;
    } 
    //删除节点
    public void delNode(int no) {
        if(root != null) {
        //如果只有一个root节点，这里需要判断root是不是要删除的节点。
            if(root.getNo() == no) {
                root = null;
            }else {
                //递归删除
                root.delNode(no);
            }
            
        }else {
            System.out.println("树空，无法删除");
        }
    }
    //前序遍历
    public void preOrder() {
        if(this.root != null) {
            this.root.preOrder();
        }else {
            System.out.println("二叉树为空，无法遍历");
        }
    }
    
    //中序遍历
    public void infixOrder() {
        if(this.root != null) {
            this.root.infixOrder();
        }else {
            System.out.println("二叉树为空，无法遍历");
        }
    }
    
    //后序遍历
    public void postOrder() {
        if(this.root != null) {
            this.root.postOrder();
        }else {
            System.out.println("二叉树为空，无法遍历");
        }
    }
    //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 root.postOrdersearch(no);
        }else {
            return null;
        }
    }
}

//先创建HeroNode节点
class HeroNode{
    private int no;
    private String name;
    private HeroNode left;
    private HeroNode right;
    public HeroNode(int no, String name) {
        this.no = no;
        this.name = name;
    }
    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;
    }
    
    @Override
    public String toString() {
        return "HeroNode [no=" + no + ", name=" + name + "]";
    }
    
    //递归删除节点
    //叶子节点则删除，非叶子节点，则要删除子树
    public void delNode(int no) {
        if(this.left != null && this.left.no == no) {
            this.left = null;
            return;
        }
        if(this.right != null && this.right.no ==no) {
            this.right = null ;
            return ;
        }
        if(this.left != null) {
            this.left.delNode(no);
        }
        if(this.right != null) {
            this.right.delNode(no);
        }
    }
    
    //编写前序遍历的方法
    public void preOrder() {
        System.out.println(this); //
        //递归向左子数
        if(this.left != null) {
            this.left.preOrder();
        }
        //递归向右前序遍历
        if(this.right!=null) {
            this.right.preOrder();
        }
        
    }
    //中序遍历
    public void infixOrder() {
        //递归向左子树中序遍历
        if(this.left != null) {
            this.left.infixOrder();
        }
        System.out.println(this);
        if(this.right != null) {
            this.right.infixOrder();
        }
    }
    
    //后续遍历
    public void postOrder() {
        if(this.left != null) {
            this.left.postOrder();
        }
        if(this.right != null) {
            this.right.postOrder();
        }
        System.out.println(this);
    }
    //前序遍历查找
    public HeroNode preOrdersearch(int no) {
        //比较当前节点是不是
        if(this.no==no) {
            return this;
        }
        HeroNode resNode =null;
        if(this.left != null) {
            resNode = this.left.preOrdersearch(no);
        }
        if(resNode != null) {
            return resNode;
        }
        if(this.right != null) {
            resNode = this.right.preOrdersearch(no);
        }
        return resNode;
    }
    //中序遍历查找
    public HeroNode infixOrdersearch(int no) {
        
        HeroNode resNode =null;
        if(this.left != null) {
            resNode = this.left.infixOrdersearch(no);
        }
        if(resNode != null) {
            return resNode;
        }
        if(this.no==no) {
            return this;
        }
        if(this.right != null) {
            resNode = this.right.infixOrdersearch(no);
        }
        return resNode;
    }
        //后序遍历查找
        public HeroNode postOrdersearch(int no) {
            HeroNode resNode =null;
            if(this.left != null) {
                resNode = this.left.postOrdersearch(no);
            }
            if(resNode != null) {
                return resNode;
            }
            if(this.right != null) {
                resNode = this.right.postOrdersearch(no);
            }
            if(resNode != null) {
                return resNode;
            }
            
            if(this.no==no) {
                return this;
            }
            return resNode;
        }
}