二叉树-查找指定节点
接上一篇博客
要求：
请编写前序查找，中序查找和后序查找的方法。
并分别使用三种查找方式，查找 heroNO = 5 的节点
代码示例：
package com.wxit.tree;
/**
* @Author wj
**/
public class BinaryTreeDemo {
public static void main(String[] args) {
//先创建一颗二叉树
BinaryTree binaryTree = new BinaryTree();
//创建需要的节点
HeroNode root = new HeroNode(1, "吴杰");
HeroNode node2 = new HeroNode(2, "吴昊");
HeroNode node3 = new HeroNode(3, "小昊");
HeroNode node4 = new HeroNode(4, "张三");
HeroNode node5 = new HeroNode(5, "李婷");
//先手动创建二叉树
root.setLeft(node2);
root.setRight(node3);
node3.setRight(node4);
node3.setLeft(node5);
binaryTree.setRoot(root);
//测试
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();
//测试
System.out.println("前序遍历查找");
HeroNode resNode = binaryTree.preOrderSearch(5);
if (resNode != null){
System.out.printf("找到了,信息为no=%d name=%s",resNode.getNo(),resNode.getName());
} else {
System.out.printf("没有找到no = %d 的英雄",5);
}
}
}
//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 + '\'' +
'}';
}
//编写前序遍历的方法
public void preOrder(){
System.out.println(this);//先输出父节点
//递归向左子树前序遍历
if (this.left != null){
this.left.preOrder();
}
//递归向右子树前序遍历
if (this.right != null){
this.right.preOrder();
}
}
//编写中序遍历的方法
public void infixOrder(){
//递归向左子树中序遍历
if (this.left != null){
this.left.infixOrder();
}
//输出父节点
System.out.println(this);
//递归向右子树中序遍历
if (this.right != null){
this.right.infixOrder();
}
}
//编写后序遍历的方法
public void postOrder(){
if (this.left != null){
this.left.postOrder();
}
if (this.right != null){
this.right.postOrder();
}
System.out.println(this);
}
//前序遍历查找
public HeroNode preOrderSearch(int no){
//比较当前节点是不是
if (this.no == no){
return this;
}
//判断当前节点的左子节点是否为空,如果不为空,则递归前序查找,如果左递归前序查找，找到节点，则返回
HeroNode resNode = null;
if (this.left != null){
resNode = this.left.preOrderSearch(no);
}
if (resNode != null){
//说明左子树找到
return resNode;
}
//左子节点没有找到，继续判断，判断当前节点的右子节点是否为空,如果不为空，就继续向右递归查找
if (this.right != null){
resNode = this.right.preOrderSearch(no);
}
return resNode;
}
//中序遍历查找
public HeroNode infixOrderSearch(int no){
//判断当前节点的左子节点是否为空,如果不为空,则递归中序查找
HeroNode resNode = null;
if (this.left != null){
resNode = this.left.infixOrderSearch(no);
}
if (resNode != null){
return resNode;
}
//没找到，就和当前节点比较,如果是，就返回
if (this.no == no){
return this;
}
//否则继续向右递归进行中序查找
if (this.right != null){
resNode = this.right.infixOrderSearch(no);
}
return resNode;
}
//后序遍历查找
public HeroNode postOrderSearch(int no){
//判断当前节点的左子节点是否为空,如果不为空,则递归后序查找
HeroNode resNode = null;
if (this.left != null){
resNode = this.left.postOrderSearch(no);
}
if (resNode != null){
return resNode;
}
//如果左子树没有找到,则向右子树递归进行后序遍历查找
if (this.right != null){
resNode = this.right.postOrderSearch(no);
}
if (resNode != null){
return resNode;
}
//如果右子树没有找到,就比较当前节点是不是
if (this.no == no){
return this;
}
return resNode;
}
}
//定义二叉树
class BinaryTree{
private HeroNode 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,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,不能遍历");
}
}
//后序遍历
public void postOrder(){
if (this.root != null){
this.root.postOrder();
} else {
System.out.println("二叉树为空,不能遍历");
}
}
//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 postOrderSearch(no);
} else {
return null;
}
}
}