递归查找所有的子集

function getSubs($categorys,$catId=0,$level=1)
{
    $subs = array();
    foreach ($categorys as $item) {
        if ($item['parentId'] == $catId) {
            $item['level'] = $level;
            $subs[] = $item;
            $subs = array_merge($subs, getSubs($categorys, $item['categoryId'], $level + 1));

        }

    }
    return $subs;
}