二叉樹-查找指定節點

并分别使用三種查找方式，查找 heroNO = 5 的節點

代碼示例：

package com.wxit.tree;

/**
 * @Author wj
 **/
public class BinaryTreeDemo {
    public static void main(String[] args) {
        //先建立一顆二叉樹
        BinaryTree binaryTree = new BinaryTree();
        //建立需要的節點
        HeroNode root = new HeroNode(1, "吳傑");
        HeroNode node2 = new HeroNode(2, "吳昊");
        HeroNode node3 = new HeroNode(3, "小昊");
        HeroNode node4 = new HeroNode(4, "張三");
        HeroNode node5 = new HeroNode(5, "李婷");

        //先手動建立二叉樹
        root.setLeft(node2);
        root.setRight(node3);
        node3.setRight(node4);
        node3.setLeft(node5);
        binaryTree.setRoot(root);

        //測試
        System.out.println("前序周遊");
        binaryTree.preOrder();

        System.out.println("中序周遊");
        binaryTree.infixOrder();

        System.out.println("後序周遊");
        binaryTree.postOrder();

        //測試
        System.out.println("前序周遊查找");
        HeroNode resNode = binaryTree.preOrderSearch(5);
        if (resNode != null){
            System.out.printf("找到了,資訊為no=%d name=%s",resNode.getNo(),resNode.getName());
        } else {
            System.out.printf("沒有找到no = %d 的英雄",5);
        }
    }
}

//建立HeroNode節點
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 + '\'' +
                '}';
    }

    //編寫前序周遊的方法
    public void preOrder(){
        System.out.println(this);//先輸出父節點
        //遞歸向左子樹前序周遊
        if (this.left != null){
            this.left.preOrder();
        }
        //遞歸向右子樹前序周遊
        if (this.right != null){
            this.right.preOrder();
        }
    }

    //編寫中序周遊的方法
    public void infixOrder(){
        //遞歸向左子樹中序周遊
        if (this.left != null){
            this.left.infixOrder();
        }
        //輸出父節點
        System.out.println(this);
        //遞歸向右子樹中序周遊
        if (this.right != null){
            this.right.infixOrder();
        }
    }

    //編寫後序周遊的方法
    public void postOrder(){
        if (this.left != null){
            this.left.postOrder();
        }
        if (this.right != null){
            this.right.postOrder();
        }
        System.out.println(this);
    }

    //前序周遊查找
    public HeroNode preOrderSearch(int no){
        //比較目前節點是不是
        if (this.no == no){
            return this;
        }
        //判斷目前節點的左子節點是否為空,如果不為空,則遞歸前序查找,如果左遞歸前序查找，找到節點，則傳回
        HeroNode resNode = null;
        if (this.left != null){
            resNode = this.left.preOrderSearch(no);
        }
        if (resNode != null){
            //說明左子樹找到
            return resNode;
        }
        //左子節點沒有找到，繼續判斷，判斷目前節點的右子節點是否為空,如果不為空，就繼續向右遞歸查找
        if (this.right != null){
            resNode = this.right.preOrderSearch(no);
        }
        return resNode;
    }

    //中序周遊查找
    public HeroNode infixOrderSearch(int no){
        //判斷目前節點的左子節點是否為空,如果不為空,則遞歸中序查找
        HeroNode resNode = null;
        if (this.left != null){
            resNode = this.left.infixOrderSearch(no);
        }
        if (resNode != null){
            return resNode;
        }
        //沒找到，就和目前節點比較,如果是，就傳回
        if (this.no == no){
            return this;
        }
        //否則繼續向右遞歸進行中序查找
        if (this.right != null){
            resNode = this.right.infixOrderSearch(no);
        }
        return resNode;
    }

    //後序周遊查找
    public HeroNode postOrderSearch(int no){
        //判斷目前節點的左子節點是否為空,如果不為空,則遞歸後序查找
        HeroNode resNode = null;
        if (this.left != null){
            resNode = this.left.postOrderSearch(no);
        }
        if (resNode != null){
            return resNode;
        }
        //如果左子樹沒有找到,則向右子樹遞歸進行後序周遊查找
        if (this.right != null){
            resNode = this.right.postOrderSearch(no);
        }
        if (resNode != null){
            return resNode;
        }
        //如果右子樹沒有找到,就比較目前節點是不是
        if (this.no == no){
            return this;
        }
        return resNode;
    }
}

//定義二叉樹
class BinaryTree{
    private HeroNode root;

    public void setRoot(HeroNode root){
        this.root = root;
    }

    //前序周遊
    public void preOrder(){
        if (this.root != null){
            this.root.preOrder();
        } else {
            System.out.println("二叉樹為空,無法周遊");
        }
    }

    //中序周遊
    public void infixOrder(){
        if (this.root != null){
            this.root.infixOrder();
        } else {
            System.out.println("二叉樹為空,不能周遊");
        }
    }

    //後去周遊
    public void postOrder(){
        if (this.root != null){
            this.root.postOrder();
        } else {
            System.out.println("二叉樹為空,不能周遊");
        }
    }

    //前序周遊
    public HeroNode preOrderSearch(int no){
        if (root != null){
            return root.preOrderSearch(no);
        }else {
            return null;
        }
    }

    //中序周遊
    public HeroNode infixOrderSearch(int no){
        if (root != null){
            return root.infixOrderSearch(no);
        } else {
            return null;
        }
    }

    //後序周遊
    public HeroNode postOrderSearch(int no){
        if (root != null){
            return postOrderSearch(no);
        } else {
            return null;
        }
    }
}