Online PHP editor | refs for nuDho

<?php $array = [ "53" => "q", "61" => "f", "74" => "s", "87" => "C", "19" => "D", "101" => "e", "22" => "C", "13" => "h" ]; $whitelist = array_fill_keys(['C', 'D'], 0); $result = []; foreach ($array as $k => $v) { if (isset($whitelist[$v])) { if ($whitelist[$v]) { break; } ++$whitelist[$v]; } if (array_sum($whitelist)) { $result[] = $k; } } var_export($result);