<?php
$input = 'abca
aaa';

$lines = explode("\n", $input);

foreach ($lines as $line)
{
	$sorted = str_split($line);
	sort($sorted);
	$words  = find_anagrams(implode($sorted));
	unset($sorted);
	$num_words = sizeof($words);
	for ($i = 0; $i < $num_words; ++$i)
	{
		if ($words[$i] <= $line)
		{
			unset($words[$i]);
		}
	}
	if (sizeof($words))
	{
		var_dump(array_shift($words));
	}
	else
	{
		var_dump('no word');
	}
	unset($words);
}

function find_anagrams($word)
{
	$len = strlen($word);
	switch ($len)
	{
		case 0:
			return array();
		break;

		case 1:
			return array($word);
		break;

		default:
			$anagrams = array();
			for ($pos = 0; $pos < $len; ++$pos)
			{
				$char = $word[$pos];

				if ($pos > 0 && $char === $word[$pos -1])
				{
					continue;
				}

				$remaining = substr_replace($word, '', $pos, 1);
				$next_anagrams = find_anagrams($remaining);

				foreach ($next_anagrams as $next_anagram)
				{
					$anagrams[] = $char . $next_anagram;
				}
			}
			return $anagrams;
		break;
	}
}

?>