Java 平衡二叉树实现

Posted 2021-02-12 currentTimeMillis

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记录一下某次使用平衡二叉树。

注：二叉树概念

【

1、二叉树、完全二叉树、满二叉树、平衡二叉树区别

二叉树： 除了叶子节点外，每个节点只有两个分支，左子树和右子树，每个节点的最大度数为2

满二叉树：除了叶结点外每一个结点都有左右子叶且叶结点都处在最底层的二叉树。

完全二叉树：只有最下面的两层结点度小于2，并且最下面一层的结点都集中再该层最左边的若干位置的二叉树

-- 满二叉树一定是完全二叉树，完全二叉树不一定是满二叉树

平衡二叉树（AVL树）：树的左右子树的高度差不超过1的数，空树也是平衡二叉树的一种。

】

一、首先要有两个实体类：

ListNode.java 链表树类

package test;

public class ListNode {
    Object val;
    ListNode next;
    ListNode(Object x) { val = x; }
}

TreeNode.java 二叉树类

package test;

public class TreeNode {
    Object val;
    TreeNode left;
    TreeNode right;
    TreeNode(Object x) { val = x; }
}

二、TreeNodeTest.java 测试类 int 数据类型

package test;

import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Date;
import java.util.List;
import java.util.Map;

public class TreeNodeTest {
    
    TreeNode treeNode =  null;
    
    @SuppressWarnings("unchecked")
    public static void main(String[] args) {
        new TreeNodeTest().test();
    }
    
    public void test() {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss SSS");
        System.out.println("================begin :"+sdf.format(new Date()));
        
        List list = new ArrayList();
        for(int i = 1 ; i< 10; i++) {
            list.add( 3*i );
        }
        System.out.println("=======add 10000 list :"+sdf.format(new Date())+" | value :"+ list);
        
        Collections.sort(list);
        System.out.println("Collections.sort list :"+sdf.format(new Date())+" | value :"+ list);
         
        ListNode head = new ListNode(list.get(0));
        for(int i = 1; i < list.size(); i++) {
            addTreeNode(head, new ListNode(list.get(i)));
        }
        System.out.println("arraylist to ListNode :"+sdf.format(new Date()) );
        
        treeNode = sortedListToBST(head);
        System.out.println("======sortedListToBST :"+sdf.format(new Date()) );
    
        Object object = selectTreeNode(treeNode, 11);
        System.out.println("=======selectTreeNode :"+sdf.format(new Date())+" | return object val:"+object);
        
        clearTreeNode(treeNode);
        System.out.println("======sortedListToBST :"+sdf.format(new Date()) );
    }
    
    // list 按照设定字段排序
    public void sortList(List<Map<String, String>> list, String name) {
        Collections.sort(list, new Comparator<Map<String, String>>() {
            public int compare(Map<String, String> o1, Map<String, String> o2) {
                return (o1.get(name)).compareTo(o2.get(name));
            }
        });
    }
    
    // ListNode 转 TreeNode
    public TreeNode sortedListToBST(ListNode head)
    {
        if (null == head) return null;
        if (null == head.next)
        {
            return new TreeNode(head.val);
        }
        ListNode slow = head, fast = head.next.next;
        while (fast != null && fast.next != null)
        {
            fast = fast.next.next;
            slow = slow.next;
        }
        TreeNode node = new TreeNode(slow.next.val);
        node.right = sortedListToBST(slow.next.next);
        slow.next = null;
        node.left = sortedListToBST(head);
        return node;
    }
    
    // add listNode
    public ListNode addTreeNode(ListNode h1, ListNode h2)
    {
        if(h1.next == null) {
            h1.next = h2;
            return h1;
        }
        addTreeNode(h1.next, h2);
        return h1;
    }
    
    // 传入要查询的数据和对应要查询的二叉树
    public Object selectTreeNode(TreeNode node, int val) {
        
        if(Integer.parseInt(node.val.toString()) == val) {
            return node.val;
        }
        
        if(node.left == null && node.right == null) {
            if(Integer.parseInt(node.val.toString()) < val) {
                return node.val;
            }
            if(Integer.parseInt(node.val.toString()) > val) {
                return null;
            }
        }
        
        if(Integer.parseInt(node.val.toString()) > val && node.left != null) {
            return selectTreeNode(node.left, val);
        }
        
        if(Integer.parseInt(node.val.toString()) < val && node.right != null) {
            Object b = selectTreeNode(node.right, val);
            if(b == null) {
                return node.val;
            } else {
                return b;
            }
        }
        
        if(Integer.parseInt(node.val.toString()) > val) {
            return null;
        }
        
        return node.val;
    }
    
    // 销毁 TreeNode
    public void clearTreeNode(TreeNode node) {
        if(node != null) {
            if(node.left != null) clearTreeNode(node.left);
            if(node.right != null) clearTreeNode(node.right);
            node.val = null;
            node.left = null;
            node.right = null;
        }
    }
 
}

三、TreeNodeTest.java 测试类 list-map 数据类型

package test;

import java.text.SimpleDateFormat;
import java.util.Collections;
import java.util.Comparator;
import java.util.Date;
import java.util.List;
import java.util.Map;

import com.alibaba.fastjson.JSON;

public class TreeNodeTest {
    
    TreeNode treeNode =  null;
    Map<String, String> map = null;
    String str = "{ "code": 200, "success": true, "message": "操作成功!", "data": [   { "dateTime": "1547438663507",     "deviceType": "4010304020302#溢满传感器",     "collectionTime": "1547437663507",     "mnc": "",     "dataType": "3",     "latitude": "",     "messageId": "",     "body": "{\"deviceType\":\"HLFWT\",\"waitQueue\":0,\"msgType\":3,\"alarm\":\"NORMAL\",\"deviceId\":\"00000001\",\"version\":\"V0.0.1\"}",     "cellid": "",     "productKey": "3eERaSscrDe",     "deviceId": "0000000001",     "version": "",     "lac": "",     "onLine": "1",     "dataTypeStr": "3",     "alarm": "",     "simNum": "",     "devTypeStr": "3eERaSscrDe",     "sn": "",     "devidStr": "0000000001",     "curMapType": "-1",     "direction": "",     "longitude": ""   },   {     "dateTime": "1547437692803",     "deviceType": "4010304020302#溢满传感器",     "collectionTime": "1547437692803",     "mnc": "",     "dataType": "3",     "latitude": "",     "messageId": "",     "body": "{\"deviceType\":\"HLFWT\",\"waitQueue\":0,\"msgType\":3,\"alarm\":\"NORMAL\",\"deviceId\":\"00000001\",\"version\":\"V0.0.1\"}",     "cellid": "",     "productKey": "3eERaSscrDe",     "deviceId": "0000000001",     "version": "",     "lac": "",     "onLine": "1",     "dataTypeStr": "3",     "alarm": "",     "simNum": "",     "devTypeStr": "3eERaSscrDe",     "sn": "",     "devidStr": "0000000001",     "curMapType": "-1",     "direction": "",     "longitude": ""   }]   }";
    
    
    @SuppressWarnings("unchecked")
    public static void main(String[] args) {
        new TreeNodeTest().test();
    }
    
    public void test() {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss SSS");
        
        Map maps = (Map)JSON.parse(str);  
        
        List<Map<String, String>> list =  (List<Map<String, String>>) maps.get("data");
        System.out.println("data to list : "+list);
        
        sortList(list, "dateTime");
        System.out.println("data to list sort : "+list);
        
        ListNode head = new ListNode(list.get(0));
        for(int i = 1; i < list.size(); i++) {
            addTreeNode(head, new ListNode(list.get(i)));
        }
        System.out.println("arraylist to ListNode :"+sdf.format(new Date()));
        treeNode = sortedListToBST(head);
        System.out.println("======sortedListToBST :"+sdf.format(new Date()));
    
        Object object = selectTreeNode(treeNode, 1547437763517l);
        System.out.println("========selectTreeNode:"+sdf.format(new Date())+" | return object val:"+object);
        
        clearTreeNode(treeNode);
        System.out.println("======sortedListToBST :"+sdf.format(new Date()));
    }
    
    // list 按照设定字段排序
    public void sortList(List<Map<String, String>> list, String name) {
        Collections.sort(list, new Comparator<Map<String, String>>() {
            public int compare(Map<String, String> o1, Map<String, String> o2) {
                return (o1.get(name)).compareTo(o2.get(name));
            }
        });
    }
    
    // ListNode 转 TreeNode
    public TreeNode sortedListToBST(ListNode head)
    {
        if (null == head) return null;
        if (null == head.next)
        {
            return new TreeNode(head.val);
        }
        ListNode slow = head, fast = head.next.next;
        while (fast != null && fast.next != null)
        {
            fast = fast.next.next;
            slow = slow.next;
        }
        TreeNode node = new TreeNode(slow.next.val);
        node.right = sortedListToBST(slow.next.next);
        slow.next = null;
        node.left = sortedListToBST(head);
        return node;
    }
    
    // add listNode
    public ListNode addTreeNode(ListNode h1, ListNode h2)
    {
        if(h1.next == null) {
            h1.next = h2;
            return h1;
        }
        addTreeNode(h1.next, h2);
        return h1;
    }
    
    // 传入要查询的数据和对应要查询的二叉树  , 返回二叉树对应结点值
    public Object selectTreeNode(TreeNode node, long val) {
        map = (Map<String, String>) node.val;
        
        if(val == Long.parseLong(map.get("dateTime").toString())) {
            return node.val;
        }
        
        if(node.left == null && node.right == null) {
            if(Long.parseLong(map.get("dateTime").toString()) < val) {
                return node.val;
            }
            if(Long.parseLong(map.get("dateTime").toString()) > val) {
                return null;
            }
        }
        
        if(Long.parseLong(map.get("dateTime").toString()) > val && node.left != null) {
            return selectTreeNode(node.left, val);
        }
        
        if(Long.parseLong(map.get("dateTime").toString()) < val && node.right != null) {
            Object b = selectTreeNode(node.right, val);
            if(b == null) {
                return node.val;
            } else {
                return b;
            }
        }
        
        if(Long.parseLong(map.get("dateTime").toString()) > val) {
            return null;
        }
        
        return node.val;
    }
    
    // 销毁 TreeNode
    public void clearTreeNode(TreeNode node) {
        if(node != null) {
            if(node.left != null) clearTreeNode(node.left);
            if(node.right != null) clearTreeNode(node.right);
            node.val = null;
            node.left = null;
            node.right = null;
        }
    }
 
}

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