- array_intersect: documentation ( source)
<?php
$a = 'acdmnprst';
$b = 'abcdefghijlmnopqrstuvz';
$al = strlen($a);
$bl = strlen($b);
$vowels = array('a', 'e', 'i', 'o', 'u', 'y');
for ($i = 0; $i < $al; $i++) {
for ($j = 0; $j < $bl; $j++) {
for ($k = 0; $k < $bl; $k++) {
$arr = array($b[$j], $b[$k], $a[$i]);
if (0 !== count(array_intersect($arr, $vowels))) {
echo $b[$j] . $b[$k] . $a[$i] . "\n";
}
}
}
}