二叉树的基本操作

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;
	}

}