php - Calculating Treversal Tree items level -

i have database has category names. columns id | categoryname | parentid. i'm using row_array() codeigniter model, , want add level key row array. have helper function recursively calculates category levels. wrote helper function in following code segment:

function treegenerate($arrs, $parent_id=0, $level=0) {     foreach($arrs $arr){         if($arr["categoryparent"]!=0){             $level+=1;         }         $arr["level"] = $level;         treegenerate($arrs,$arr["categoryparent"],$level);     }     return $arrs; } 

but gives error: "allowed memory size of 33554432 bytes exhausted (tried allocate 523800 bytes)". how can fix problem?

just thoughts without knowing code:

• is possible add level keys starting trunk? might save repetition.
• can move foreach outside of treegenerate?

like:

function treegenerate($arr,$level=0) {         if($arr["categoryparent"]!=0){            $level +=1;         }         else return $level;       }     treegenerate($arr["categoryparent"],$level);; }  foreach ($arrs $arr) $arr['level'] =  treegenerate($arr);