RosettaCodeData/Task/Primality-by-trial-division/PHP/primality-by-trial-division-2.php
Ingy döt Net b83f433714 tasks a-s
2013-04-10 23:57:08 -07:00

5 lines
97 B
PHP

<?php
function prime($a) {
return !preg_match('/^1?$|^(11+?)\1+$/', str_repeat('1', $a));
}
?>