Could you tell me a sorting algorithm for php array?

has an array. 

$a=[
     ["id"=>1,name="w1"],
     ["id"=>4,name="w3"],
     ["id"=>3,name="w2"],
     ["id"=>5,name="w5"],
     ["id"=>6,name="w22"],
     ["id"=>8,name="w222"],
     ["id"=>30,name="w30"]
   ];

how did it become like this? 

$a=[
     ["id"=>1, name="w1",  "sn"=>11],
     ["id"=>4, name="w3",  "sn"=>21],
     ["id"=>3, name="w2",  "sn"=>22],
     ["id"=>5, name="w5",  "sn"=>31],
     ["id"=>6, name="w22", "sn"=>32],
     ["id"=>8, name="w222","sn"=>33],
     ["id"=>30,name="w30", "sn"=>34]
   ];
The change of

sn begins with the power of 2 to the power of 0, and the change begins with the change of 2 to the power of 2 and 4 to 8. If there is any data below, it may be next time. 41,42,43,44,45,46,47,48 .

I can"t figure it out. It looks very simple. I don"t know how to start. It doesn"t matter how you write it. I"d like to ask a master to help me. Thank you!

sn comes in order, which is not convenient. Do not press id,name. In the present order.

Php algorithm
May.11,2021 
$a=[
 ['id'=>1,'name'=>'w1'],
 ['id'=>4,'name'=>'w3'],
 ['id'=>3,'name'=>'w2'],
 ['id'=>5,'name'=>'w5'],
 ['id'=>6,'name'=>'w22'],
 ['id'=>8,'name'=>'w222'],
 ['id'=>30,'name'=>'w30'],
 ['id'=>30,'name'=>'w30'],
 ['id'=>30,'name'=>'w30'],
 ['id'=>30,'name'=>'w30'],
 ['id'=>30,'name'=>'w30'],
 ['id'=>30,'name'=>'w30'],
 ['id'=>30,'name'=>'w30'],
   ];
function add_sn(&$arr){
    $len=count($arr);
   $j=0;
   $n=0;
   for ($i=1;$i<=pow(2,$n);$iPP) { 
        $arr[$j]['sn']=($n+1).$i;
        if($i==pow(2,$n)){
            $i=0;
            $nPP;
        }
        $jPP;
        if($j==$len){
            return;
        }
   }    
   }

   
   add_sn($a);
   print_r($a);

Previous: In vue+typescript, use axios to report an error?

Next: Every time expandedRowKeys gets it, it doesn't work?

css mysql arrays josn react html typescript webpack npm sass R objective-c .net sql-server jquery python-3.x angularjs django angular excel regex iphone ajax linux xml pandas vba spring database wordpress string wpf xcode windows bash postgresql oracle multithreading eclipse list firebase algorithm macos forms image scala visual-studio azure bootstrap spring-boot react-native python-2.7 docker performance function winforms matlab powershell apache dataframe api sqlite numpy rest shell selenium flutter dart maven loops qt swing android-studio csv express file class tensorflow sorting codeigniter perl
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b2b561-2ba9c.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b2b561-2ba9c.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
Need Help?