How are infinite paternity trees sorted?

The

data structure looks like this. {id:parentIds} id is unique, and parentIds stores the ids. of the superior. For example, if the id=9 parentIds under the id=5 under the parent class is id=1, the parentIds at the highest level is 0, so how do you sort it?

for example, the current data is:

array(
    "1"=>"0",
    "2"=>"0",
    "3"=>"0",
    "4"=>"1",
    "5"=>"1",
    "6"=>"2",
    "7"=>"1",
    "8"=>"1",
    "9"=>"2",
    "10"=>"3",
    "11"=>"3",
    "12"=>"2",
    "13"=>"1",
    "14"=>"1,8",
    "15"=>"1,8,14",
    "16"=>"2,9",
    "17"=>"1,8",
    "18"=>"3,10",
    "19"=>"3,11",
    "20"=>"3,10,18",
    "21"=>"1,8,14,15",
    "22"=>"1,8,14");

after processing (siblings may not be in order):

array(
    "1"=>"0",
    "4"=>"1",
    "5"=>"1",
    "7"=>"1",
    "8"=>"1",
    "14"=>"1,8",
    "15"=>"1,8,14",
    "22"=>"1,8,14");
    "21"=>"1,8,14,15",
    "17"=>"1,8",
    "13"=>"1",
    "2"=>"0",
    "6"=>"2",
    "9"=>"2",
    "16"=>"2,9",
    "12"=>"2",
    "3"=>"0",
    "10"=>"3",
    "18"=>"3,10",
    "20"=>"3,10,18",
    "11"=>"3",
    "19"=>"3,11",

$a = [ '1' => '0', '2' => '0', '3' => '0', '4' => '1', '5' => '1', '6' => '2', '7' => '1', '8' => '1', '9' => '2', '10' => '3', '11' => '3', '12' => '2', '13' => '1', '14' => '1,8', '15' => '1,8,14', '16' => '2,9', '17' => '1,8', '18' => '3,10', '19' => '3,11', '20' => '3,10,18', '21' => '1,8,14,15', '22' => '1,8,14', ]; $result = treeSort($a); print_r($result); function treeSort($arr) { $list = []; foreach ($arr as $key => $item) { $version = $item == 0 ? $item : ('0.' . $item); $list[] = [$key, str_replace(',', '.', $version) . '.' . $key]; } $mySort = function ($a, $b) { return version_compare($a[1], $b[1], 'ge'); }; usort($list, $mySort); $tree = []; foreach ($list as $item) { $tree[$item[0]] = $arr[$item[0]]; } return $tree; }