package Tree;
import java.util.Scanner;
public class TreeApp {
private static Scanner input = new Scanner(System.in);
public static void main(String[] args) {
Node root = null;//root为指向二叉树的根节点的引用
int operation;//操作
//设置根节点
root = init();
//添加节点
do{
System.out.println("请选择菜单添加二叉树的节点");
System.out.println("0：退出");
System.out.println("1:添加二叉树的节点");
operation = input.nextInt();
switch(operation){
case 1:
add(root);
break;
case 0:
break;
}
}while(operation != 0);
//遍历二叉树
do{
System.out.println("请选择菜单遍历二叉树，输入0表示退出");
System.out.println("1：先序遍历");
System.out.println("2：中序遍历");
System.out.println("3:后序遍历" );
System.out.println("4:按层遍历" );
operation = input.nextInt();
switch(operation){
case 0:
break;
case 1:
System.out.println("先序遍历的结果：");
DLR(root);
System.out.println();
break;
case 2:
System.out.println("中序遍历的结果：");
LDR(root);
System.out.println();
break;
case 3:
System.out.println("后序遍历的结果：");
LRD(root);
System.out.println();
break;
case 4:
System.out.println("层遍历的结果：");
Level(root);
System.out.println();
break;
}
}while(operation != 0);
//深度
System.out.printf("输出二叉树的深度：%d",Depth(root));
//清空二叉树
Clear(root);
root = null;
}
private static void Clear(Node root) {
if(root != null){
Clear(root.leftChild);
Clear(root.rightChild);
root = null;
}
}
private static int Depth(Node root) {
int depleft,depright;
if(root == null){
return 0;
}else{
depleft = Depth(root.leftChild);//左子树递归
depright = Depth(root.rightChild);//右子树递归
if(depleft > depright){
return depleft+1;
}else{
return depright+1;
}
}
}
private static void Level(Node root) {//按层遍历
Node p;
Node[] q = new Node[20];
int head=0;
int tail = 0;
//如果队首的引用的不为空
if(root != null){
//计算循环队列的队尾的号
tail = (tail+1)%20;
q[tail] = root;//将二叉树根引用进队
}
while(head != tail){//队列不为空,进行循环
//计算循环队列的队首编号
head = (head+1)%20;
p = q[head];//获取队首的元素
NodeData(p);//处理队首元素
//如果节点存在左子树
if(p.leftChild != null){
tail = (tail+1)%20;
q[tail] = p.leftChild;//将左子树引进队列
}
if(p.rightChild != null){
tail = (tail+1)%20;
q[tail] = p.rightChild;//将左子树引进队列
}
}
}
private static void LRD(Node root) {
if(root != null){
LRD(root.leftChild);
LRD(root.rightChild);
NodeData(root);
}
}
private static void LDR(Node root) {
if(root != null){
LDR(root.leftChild);
NodeData(root);
LDR(root.rightChild);
}
}
private static void DLR(Node root) {
//先序遍历
if(root != null){
//显示节点的数据
NodeData(root);
DLR(root.leftChild);
DLR(root.rightChild);
}
}
private static void NodeData(Node root) {
System.out.print(root.iData +" ");
}
private static void add(Node root) {//添加节点
Node pNode,parent;
int data;
int oper;
if((pNode = new Node()) != null){//分配内存
System.out.println("输入二叉树节点的数据");
pNode.iData = input.nextInt();
pNode.leftChild = null;
pNode.rightChild = null;
System.out.println("输入该节点父节点的值");
data = input.nextInt();
//查找指定数据的节点
parent = Find(root,data);
//如果没有找到
if(parent == null){
System.out.println("没有找到父节点");
pNode = null;//释放内存
return;
}
System.out.println("1：添加左子树；2：添加右子树");
do{
oper = input.nextInt();//输入选择项
if(oper ==1||oper==2){
if(parent == null){
System.out.println("不存在父节点，请先设置父节点");
}else{
switch(oper){
case 1://添加到左节点,左子树不为空
if(parent.leftChild != null){
System.out.println("左子树不为空");
}else{
parent.leftChild = pNode;
}
break;
case 2://添加到右节点，右子树不为空
if(parent.rightChild != null){
System.out.println("左子树不为空");
}else{
parent.rightChild = pNode;
}
break;
default:
System.out.println("无效的参数");
}
}
}
}while(oper!=1 && oper!= 2);
}
}
private static Node Find(Node root, int data) {
Node current = root;
if(root == null){
return null;
}else{
if(root.iData == data){
return root;
}else{//分别向左子树，和右子树递归
if((current = Find(root.leftChild,data)) != null){
return current;
}else if((current = Find(root.rightChild,data)) != null){
return current;
}else{
return null;
}
}
}
}
private static Node init() {
Node node = new Node();
if(node != null){
System.out.println("请先输入根的数据");
node.iData =input.nextInt();
node.leftChild = null;
node.rightChild = null;
if(node != null){
return node;
}
}
return null;
}
}
