用Java實現二進制搜索樹

Question

這是我為二進制搜索樹編寫的代碼。 不幸的是，當我運行它時，它沒有給出期望的輸出。 有人可以告訴我我在做什么錯。

import java.util.ArrayList;


public class BinaryOrderedTree {
    BinaryOrderedTree left;
    BinaryOrderedTree right;
    static BinaryOrderedTree top;
    int key;
    static ArrayList<BinaryOrderedTree> values=new ArrayList<BinaryOrderedTree>();



    public int getKey(){
        return key;
    }


    public void setTop(BinaryOrderedTree top1){
        top=top1;
    }

    public BinaryOrderedTree getLeft(){
        return this.left;
    }

    public BinaryOrderedTree getRight(){
        return this.right;
    }

    public BinaryOrderedTree(int key){
        this.key=key;
    }

    public static BinaryOrderedTree addNode(BinaryOrderedTree node,BinaryOrderedTree top){
        if (node.getKey()<top.getKey()){
            if(top.left==null){
                System.out.println(node.getKey());
                System.out.println("left");
            top.left=node;
            }
            else{
                addNode(node,top.left);
            }
        }
        if(node.getKey()>top.getKey()){
            if(top.right==null){
                System.out.println(node.getKey());
                System.out.println("right");
                top.right=node;
            }
            else{
                addNode(node,top.right);
            }
        }
        return node;
    }

    public static BinaryOrderedTree searchNode(BinaryOrderedTree search, 
            BinaryOrderedTree top){
        if(search.getKey()==top.getKey()){
            return top;
        }
        else if(search.getKey()<top.getKey()){
            return searchNode(search,top.left);
        }
        else if(search.getKey()>top.getKey()){
            return searchNode(search,top.right);
        }
        return null;
    }

    public static BinaryOrderedTree traverse(BinaryOrderedTree top){
        values.add(top);
        System.out.println(top.getKey());
        if(top.left !=null)
        traverse(top.left);
        else if (top.right!=null)
        traverse(top.right);
        values.add(top.left);
        values.add(top.right);
        return top;
    }   

    public static void main(String[] args){
        BinaryOrderedTree top=new BinaryOrderedTree(7);
        BinaryOrderedTree firstNode=new BinaryOrderedTree(6);

        BinaryOrderedTree.addNode(firstNode,top);
        BinaryOrderedTree secondNode=new BinaryOrderedTree(4);
        BinaryOrderedTree.addNode(secondNode, top);
        BinaryOrderedTree thirdNode=new BinaryOrderedTree(8);
        BinaryOrderedTree.addNode(thirdNode, top);
        BinaryOrderedTree fourthNode=new BinaryOrderedTree(3);
        BinaryOrderedTree.addNode(fourthNode, top);
        BinaryOrderedTree.traverse(top);
//      System.out.println(BinaryOrderedTree.values);
    }
}

This is the output I get

    6
left
4
left
8
right
3
left
traversing pre-order
7
6
4
3

我只能假設節點已正確添加。 但是，它無法顯示頂部節點右側的節點，而僅遍歷左側部分。 有人可以指出缺陷。

Answer 1

刪除右遍歷中的else ：

if(top.left !=null)
    traverse(top.left);
if (top.right!=null)
    traverse(top.right);

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順便說一句，您的values也可能會奇怪地充滿。 values.add(top)就足夠了。 刪除這些values.add(top.left)和values.add(top.right) 。

---

順便說一句（另外一個） 變量陰影並不能真正幫助您理解代碼。