<?php
$regions = [
'int' => 1,
'nl' => 2,
'be' => 4,
'us' => 8,
'as' => 16,
'za' => 32,
];
for ($i = 0; $i < 1 << count($regions); $i++) array_walk(array_filter($regions, function($x) use ($i) { return $x & $number; }), function($x, $region) use (&$list) { isset($list[$region]) && $list[$region] .= ","; $list[$region] .= $x; });
var_dump($list);
preferences:
38.01 ms | 402 KiB | 5 Q