二叉树java遍历实现

Posted 2022-08-09 zyf-yxm

假设二叉树如图:

import java.util.ArrayList;
import java.util.List;

import org.junit.Test;

public class MyTree 
    private Node root = null;

    public MyTree() 
        init();
    

    private List<Node> list = new ArrayList<Node>();

    private void init() 
        Node e = new Node("E", null, null);
        Node d = new Node("D", null, null);
        Node b = new Node("B", d, e);
        Node c = new Node("C", null, null);
        Node a = new Node("A", b, c);
        root = a;
    

    private class Node 
        private String data;

        private Node lChild;

        private Node rChild;

        public Node(String data, Node lChild, Node rChild) 
            this.data = data;
            this.lChild = lChild;
            this.rChild = rChild;
        
    

    /**
     * 深度遍历
     * 
     * */
    public int getTreeDepth(Node node) 

        if (node.lChild == null && node.rChild == null) 
            return 1;
        
        int left = 0, right = 0;
        if (node.lChild != null) 
            left = getTreeDepth(node.lChild);
        
        if (node.rChild != null) 
            right = getTreeDepth(node.rChild);
        
        return left > right ? left + 1 : right + 1;
    

    /**
     * 前序遍历:ABDEC
     * 1.首先遍历左子树,遍历到叶子结点为止
     * @return 
     * */
    public boolean preorderTraverse(Node node) 
        //首先从根节点开始遍历
        list.add(node);
        if (node.lChild != null) 
            //
            preorderTraverse(node.lChild);
        
        if (node.rChild != null) 
            preorderTraverse(node.rChild);
        
        return true;
    

    /**
     * 中序遍历:DBEAC
     * @return 
     * 
     * */
    public boolean inorderTarverse(Node node) 
        if (node.lChild != null) 
            inorderTarverse(node.lChild);
        
        list.add(node);
        if (node.rChild != null) 
            inorderTarverse(node.rChild);
        
        return true;
    

    /**
     * 后序遍历:DEBCA
     * @return 
     * 
     * */
    public boolean postorderTarverse(Node node) 
        if (node.lChild != null) 
            postorderTarverse(node.lChild);
        
        if (node.rChild != null) 
            postorderTarverse(node.rChild);
        
        list.add(node);
        return true;
    
    
    public List<Node> getList() 
        return list;
    

    @Test
    public void testGetDeth() 
        MyTree mt = new MyTree();
        System.out.println("树的深度:" + getTreeDepth(mt.root));
        //if(mt.preorderTraverse(mt.root)) System.out.print("前序遍历结果:");
        //if(mt.inorderTarverse(mt.root)) System.out.print("中序遍历结果:");
        if(mt.postorderTarverse(mt.root)) System.out.print("后序遍历结果:");
        //if(mt.sequenceTraverse(mt.root)) System.out.print("层序遍历结果:");
        for (Node node : mt.getList()) 
            System.out.print(node.data);