$a= array(
             array('category' =>
             array('name'=>"第一级"),'children' => array(
             array('category' =>
             array('name'=>"第二级"),'children' => array(
             array('category' =>
             array('name'=>"第三级")
             )
             )
             )
             )
             )
             )
             ;

$a = array(
  array('category' =>
    array('name'=>"第一级"),'children' => array(
      array('category' =>
        array('name'=>"第二级"),'children' => array(
          array('category' =>
            array('name'=>"第三级")
          )
        )
      )
    )
  )
);

function Breadcrumbs($ar) {
  foreach($ar as $row) {
    if(isset($row['category'])) echo $row['category']['name'];
    if(isset($row['children'])) {
      echo ' ';
      Breadcrumbs($row['children']);
    }
  }
}

Breadcrumbs($a);