拆分数组并组织值

我有以下PHP数组：

$b = array
(
    0 =>"03xxx", //Index of main,  substr(index,0,2)
        1 =>"04xxx",
        2 =>"05xxx",
        //3 =>"06xxx" // missing "06" 
        //4 =>"07xxx",
        6 =>"04xxx",
        7 =>"05xxx",
        8 =>"06xxx",
        //9 =>"07xxx"
    10 =>"08xxx",
    11 =>"03xxx" ,// new index of main
        12 =>"04xxx",
        13 =>"05xxx",
        14 =>"06xxx",
        //15 =>"07xxx" missing "07"
    16 =>"08xxx"
);

我需要将其转换为：

/*the expected result 
Array
(
    [0] => Array
        (
            [0] => 03xxx04xxx05xxx          08xxx, // missing 06 ,07
            [1] => 03xxx04xxx05xxx06xxx     08xxx // missing 07 
        )
    [1] => Array
        (
            [0] => 03xxx04xxx05xxx06xxx     08xxx // missing 07
        )
)
*/

更新：

根据yes123的回答，我得出了以下解决方案：

/*
 * thank to @yes123 
*/
function transform($a){
    $result=array();
    $i=0;
    $j=0;
    $last = 2;
    foreach($a as $k=>$v) {
        if (!isset($result[$i]))
            $result[$i]=array('');

        if ( ++$last != $v[1])
            $result[$i][$j] .=  str_repeat(str_pad(" ",5),($v[1]-$last));
        $result[$i][$j] .= $v;
        $last = $v[1];
        if (substr($v,0,2)=='08') {
            $last=3;
            $j++;
        }
        if ($a[$k+1][1]=='3') {
            $last=2;
            $i++;
            $j=0;
        }
    }
    return $result;
    }