二叉樹結構 統計每個葉子節點下的節點的數量

類以下：

<?php
class getUserLeftRightNumber
{
    public $arr_all;
    public $arr_init;
    public $arr_leaf;
    public $arr_res;
    public function __counstruct()
    {
    
    }

    public function getUserNum()
    {
        // ini_set('memory_limit','6144M');
        // set_time_limit(0);

        // header('content-type:text/html;charset=utf-8'); 
        // define('DB_HOST','127.0.0.1'); 
        // define('DB_USER','root'); 
        // define('DB_PASS','root'); 
        // define('DB_NAME','test'); 
        // define('DB_PORT',3306); 
        // define('DB_CHAR','utf8'); 
        // define('APPNAME',''); 
        // $mysqli = new mysqli( DB_HOST, DB_USER, DB_PASS, DB_NAME);
        // $rst = $mysqli->query( 'set names ' . DB_CHAR );
        // $sql = 'select * from ub_user_expand';
        // $result=$mysqli->query($sql);
        // $array=array(); 
        // while( $rows=$result->fetch_assoc() )
        // {
        //     $r['uid'] = $rows['uid'];
        //     $r['name'] = $rows['username'];
        //     $r['_referee'] = $rows['_referee'];
        //     $r['_left'] = $rows['_left'];
        //     $r['_right'] = $rows['_right'];
        //     $r['position'] = $rows['position'];

        //     $this->arr_all[] = $r;
        // }
        // print_r($this->arr_all);die();

        $this->arr_all[0]  = array('uid' => '10000000', '_referee' => '','name' => '101001', '_left' => '10000001', '_right' => '10000002', 'position' => '' );
        $this->arr_all[1]  = array('uid' => '10000001', '_referee' => '101001', 'name' => '102001', '_left' => '10000003', '_right' => '10000004', 'position' => 1 );
        $this->arr_all[2]  = array('uid' => '10000002', '_referee' => '101001', 'name' => '102002', '_left' => '10000005', '_right' => '10000006', 'position' => 2 );
        $this->arr_all[3]  = array('uid' => '10000003', '_referee' => '102001', 'name' => '103001', '_left' => '10000007', '_right' => '10000008', 'position' => 1 );
        $this->arr_all[4]  = array('uid' => '10000004', '_referee' => '102001', 'name' => '103002', '_left' => '10000009', '_right' => '10000010', 'position' => 2 );
        $this->arr_all[5]  = array('uid' => '10000005', '_referee' => '102002', 'name' => '103003', '_left' => '10000011', '_right' => '10000012', 'position' => 1 );
        $this->arr_all[6]  = array('uid' => '10000006', '_referee' => '102002', 'name' => '103004', '_left' => '10000013', '_right' => '10000014', 'position' => 2 );
        $this->arr_all[7]  = array('uid' => '10000007', '_referee' => '103001', 'name' => '104001', '_left' => '10000015', '_right' => '10000016', 'position' => 1 );
        $this->arr_all[8]  = array('uid' => '10000008', '_referee' => '103001', 'name' => '104002', '_left' => '10000017', '_right' => '10000018', 'position' => 2 );
        $this->arr_all[9]  = array('uid' => '10000009', '_referee' => '103002', 'name' => '104003', '_left' => '10000019', '_right' => '10000020', 'position' => 1 );
        $this->arr_all[10] = array('uid' => '10000010', '_referee' => '103002', 'name' => '104004', '_left' => '10000021', '_right' => '10000022', 'position' => 2 );
        $this->arr_all[11] = array('uid' => '10000011', '_referee' => '103003', 'name' => '104005', '_left' => '10000023', '_right' => '10000024', 'position' => 1 );
        $this->arr_all[12] = array('uid' => '10000012', '_referee' => '103003', 'name' => '104006', '_left' => '10000025', '_right' => '10000026', 'position' => 2 );
        $this->arr_all[13] = array('uid' => '10000013', '_referee' => '103004', 'name' => '104007', '_left' => '10000027', '_right' => '10000028', 'position' => 1 );
        $this->arr_all[14] = array('uid' => '10000014', '_referee' => '103004', 'name' => '104008', '_left' => '10000029', '_right' => '10000030', 'position' => 2 );
        $this->arr_all[15] = array('uid' => '10000015', '_referee' => '104001', 'name' => '105001', '_left' => '',  '_right' => '', 'position' => 1 );
        $this->arr_all[16] = array('uid' => '10000016', '_referee' => '104001', 'name' => '105002', '_left' => '',  '_right' => '', 'position' => 2 );
        $this->arr_all[17] = array('uid' => '10000017', '_referee' => '104002', 'name' => '105003', '_left' => '',  '_right' => '', 'position' => 1 );
        $this->arr_all[18] = array('uid' => '10000018', '_referee' => '104002', 'name' => '105004', '_left' => '',  '_right' => '', 'position' => 2 );
        $this->arr_all[19] = array('uid' => '10000019', '_referee' => '104003', 'name' => '105005', '_left' => '',  '_right' => '', 'position' => 1 );
        $this->arr_all[20] = array('uid' => '10000020', '_referee' => '104003', 'name' => '105006', '_left' => '',  '_right' => '', 'position' => 2 );
        $this->arr_all[21] = array('uid' => '10000021', '_referee' => '104004', 'name' => '105007', '_left' => '',  '_right' => '', 'position' => 1 );
        $this->arr_all[22] = array('uid' => '10000022', '_referee' => '104004', 'name' => '105008', '_left' => '',  '_right' => '', 'position' => 2 );
        $this->arr_all[23] = array('uid' => '10000023', '_referee' => '104005', 'name' => '105009', '_left' => '',  '_right' => '', 'position' => 1 );
        $this->arr_all[24] = array('uid' => '10000024', '_referee' => '104005', 'name' => '105010', '_left' => '',  '_right' => '', 'position' => 2 );
        $this->arr_all[25] = array('uid' => '10000025', '_referee' => '104006', 'name' => '105011', '_left' => '',  '_right' => '', 'position' => 1 );
        $this->arr_all[26] = array('uid' => '10000026', '_referee' => '104006', 'name' => '105012', '_left' => '',  '_right' => '', 'position' => 2 );
        $this->arr_all[27] = array('uid' => '10000027', '_referee' => '104007', 'name' => '105013', '_left' => '',  '_right' => '', 'position' => 1 );
        $this->arr_all[28] = array('uid' => '10000028', '_referee' => '104007', 'name' => '105014', '_left' => '',  '_right' => '', 'position' => 2 );
        $this->arr_all[29] = array('uid' => '10000029', '_referee' => '104008', 'name' => '105015', '_left' => '',  '_right' => '', 'position' => 1 );
        $this->arr_all[30] = array('uid' => '10000030', '_referee' => '104008', 'name' => '105016', '_left' => '',  '_right' => '', 'position' => 2 );


        // 循環處理數據 獲取 葉子節點
        foreach ( $this->arr_all as $key => $value ) 
        {
            $this->arr_init[$value['name']] = $value;
            if ( empty( $value['_left'] ) && empty( $value['_right'] ) ) 
            {
                $this->arr_leaf[] = $value;
            }
        }

        foreach ( $this->arr_leaf as $key => $value ) 
        {
            $this->getUserNumInit( $this->arr_init, $value, 0 );
        }

        print_r( $this->arr_res );
    
    }

    public function getUserNumInit( $all, $leaf, $count_last )
    {
        if ( !empty( $leaf ) && is_array( $leaf ) && !empty($leaf['_referee']) ) 
        {
            // echo '<br/>'.$leaf['name'].'<br/>';
            $count      = 0;
            $count_self = 1;
            $count_all  = $count_self + $count_last;

            $res_key    = $leaf['_referee'];

            $this->arr_res[$res_key]['uid'] = $this->arr_init[$leaf['_referee']]['uid'];
            $this->arr_res[$res_key]['uname'] = $res_key;

            if ( $leaf['position'] == 'left' ) 
            {
                $this->arr_res[$res_key]['numLeft'] = $count_all;
                $count = $count_all;

                if ( isset( $this->arr_res[$res_key]['numRight']) ) 
                {
                    $count = $this->arr_res[$res_key]['numLeft'] + $this->arr_res[$res_key]['numRight'];
                }
            }
            elseif ( $leaf['position'] == 'right' ) 
            {
                $this->arr_res[$res_key]['numRight'] = $count_all;
                $count = $count_all;
                if ( isset( $this->arr_res[$res_key]['numLeft']) ) 
                {
                    $count = $this->arr_res[$res_key]['numLeft'] + $this->arr_res[$res_key]['numRight'];
                }
            }
            else 
            {
                return false;
            }

            // 獲取上級、而後遞歸
            $referee = isset($all[$leaf['_referee']])&&!empty($leaf['_referee']) ? $all[$leaf['_referee']] : '';
            if ( !empty( $referee ) ) 
            {
                $this->getUserNumInit( $all, $referee, $count );
            }

        }
    }
}

使用

$obj = new getUserLeftRightNumber();
$obj->getUserNum();