二分搜索树 添加节点、遍历、最大深度的php版本

<?php
/**
 * 节点值重复的会跳过，类似集合
 */
/**
 * 节点类  
 */ 
class Node
{
    public $value;
    public $left = null;
    public $right = null;

    
    public function __construct($value)
    {
        # code...
        $this->value = $value;
    }
}

/**
 * 操作类
 */
class tree
{
    public $root = null;//根节点
    public $size  = null; //节点个数
    public $values = []; //保存遍历树结构的值
    public $depth = 0; //树高度


    public function add($value)
    {
        if ($this->root == null) {
            $this->root = new Node($value);
            $this->size ++; 
        } else {
            // var_dump($this->root);
            $this->root = $this->insert($this->root, new Node($value));
        }

        return $this->root;
    }

    //向已root为根节点的二分搜索树种插入元素node
    public function insert($root, $node)
    {
        // var_dump($root);
        //终止条件
        if ($root == null) {
            return $node; 
        }

        if ($node->value > $root->value) {
            $root->right = $this->insert($root->right, $node);
            $this->size ++; 
        } else if ($node->value < $root->value){
            $root->left = $this->insert($root->left, $node);
            $this->size ++; 
        }
        
        return $root;
    }

    public function select($node)
    {
        //终止条件
        if ($node == null) {
            return null;
        }
        $this->values[] = $node->value;//前序遍历       
        $this->select($node->left); 
        // $this->values[] = $node->value;//中序遍历
        $this->select($node->right);    
        // $this->values[] = $node->value;//后续遍历
    }

    public function height($node, $depth)
    {

        if ($node == null) {
            return null;
        }

        $this->height($node->left, $depth + 1); 
        $this->height($node->right, $depth + 1);
        $this->depth = $this->depth < $depth + 1 ? $depth + 1 : $this->depth;

    }

}

//制作一些数据
$tree = new tree();

foreach ([28, 16, 13, 22, 30, 29, 42, 45] as  $value) {
    //添加一个值到二分搜索树中
    $tree->add($value);
}


//打印二分搜索树结构
// var_dump($tree->root);


//遍历二分搜索树结构
// $tree->select($tree->root);
// var_dump($tree->values);


//二分搜索树的高度
$tree->height($tree->root, 0);

var_dump($tree->depth);