排序二叉树（Java）

性质：

• 若左子树不为空，则左子树上的所有节点的值都小于其根节点的值；

• 若右子树不为空，则右子树上的所有节点的值都大于其根节点的值；

• 左右子树均为排序二叉树

package com.answer.binaryTree;

import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Queue;

public class SortedBinTree {
    private  static class Node{
        private Object data;
        private Node left;
        private Node right;
        private Node parent;
        public Node(Object data,Node parent,Node left,Node right){
            this.data=data;
            this.parent=parent;
            this.left=left;
            this.right=right;
        }
        public boolean compareTo(Object object){
            if(this==object){
                return true;
            }
            if(object.getClass()==Node.class){
                Node target=(Node)object;
                return data.equals(target.data)
                        &&left==target.left
                        &&right==target.right
                        &&parent==target.parent;
            }return false;
        }
        public String toString(){
            return "data:"+data;
        }
    }
    private Node root;
    public SortedBinTree(){
        root=null;
    }
    public SortedBinTree(String data){
        root=new Node(data,null,null,null);
    }
    public void insert(T data){
        if(root==null){
            root=new Node(data,null,null,null);
        }else{
            Node current=root;
            Node parrent=null;
            int cmp=0;
            do{
                parrent=current;
                cmp=data.compareTo(current.data);
                if(cmp<=0){
                    current=current.left;
                }else{
                    current=current.right;
                }
            }while(current!=null);
            Node node=new Node(data,parrent,null,null);
            if(cmp<0){
                parrent.left=node;
            }else {
                parrent.right=node;
            }
        }
    }
    public void remove(T data){
        Node target=getNode(data);
        if(target==null){
            return;
        }
        if(target.left==null&&target.right==null){
            if(target==root){
                root=null;
            }else {
                if(target==target.parent.left){
                    target.parent.left=null;
                }
                else{
                    target.parent.right=null;
                }
            }
        }else if(target.left!=null&&target.right==null){
            if(target==root){
                root=target.left;
            }else {
                if(target==target.parent.left){
                    target.parent.left=target.left;
                }
                else {
                    target.parent.right=target.left;
                }
                target.left.parent=target.parent;
            }
        }else if(target.left==null&&target.right!=null){
            if(target==root){
                root=target.right;
            }else {
                if(target==target.parent.left){
                    target.parent.left=target.right;
                }
                else{
                    target.parent.right=target.right;
                }
                target.right.parent=target.parent;
            }
        }else{//左右子树都不为空，用小于删除节点的最大子节点代替它
            Node leftMaxNode=target.left;
            while(leftMaxNode.right!=null){
                leftMaxNode=leftMaxNode.right;
            }
            leftMaxNode.parent.right=null;
            leftMaxNode.parent=target.parent;
            if(target==target.parent.left){
                target.parent.left=leftMaxNode;
            }else {
                target.parent.right=leftMaxNode;
            }
            leftMaxNode.left=target.left;
            leftMaxNode.right=target.right;
            target.parent=target.left=target.right=null;
        }
    }

    private Node getNode(T data) {
        Node current=root;
        while(current!=null){
            int cmp=data.compareTo(current.data);
            if(cmp<0){
                current=current.left;
            }else if(cmp>0){
                current=current.right;
            }else{
                return current;
            }
        }
        return null;
    }
    public ArrayList level(){
        ArrayList list=new ArrayList<>();
        Queue queue=new ArrayDeque<>();
        if(root!=null){
            queue.add(root);
        }
        while(!queue.isEmpty()){
            Node node=queue.remove();
            list.add(node);
            if(node.left!=null){
                queue.add(node.left);
            }
            if (node.right!=null){
                queue.add(node.right);
            }
        }return list;
    }

    public static void main(String[] args) {
        SortedBinTree tree=new SortedBinTree<>();
        tree.insert(5);
        tree.insert(20);
        tree.insert(10);
        tree.insert(3);
        tree.insert(8);
        tree.insert(15);
        tree.insert(30);
        tree.insert(4);
        System.out.println(tree.level());
        tree.remove(20);
        System.out.println(tree.level());
    }
}