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<?php function longest_palendrome($string) { $current = $longest = ''; foreach (str_split(strrev($string)) as $char) { if (strstr($string, $current . $char)) { $current .= $char; } elseif (!empty($current) && strlen($current) > strlen($longest)) { $longest = $current; $current = ''; } } return $longest; } echo longest_palendrome("i ama racecar ama aaaaaaaabbbbbbbbaaaaaaaa");

preferences:
56.71 ms | 402 KiB | 5 Q