2) { $arguments = \func_get_args(); \array_splice($arguments, 0, 2, [$this->solve($stringA, $stringB)]); return $this->solve(...$arguments); } $charsA = \str_split($stringA); $charsB = \str_split($stringB); $matrix = \array_fill_keys(\array_keys($charsA), \array_fill_keys(\array_keys($charsB), 0)); $longestLength = 0; $longestIndexes = []; foreach ($charsA as $i => $charA) { foreach ($charsB as $j => $charB) { if ($charA === $charB) { $matrix[$i][$j] = $i === 0 || $j === 0 ? 1 : $matrix[$i - 1][$j - 1] + 1; $newIndex = $this->newIndex($matrix, $i, $j); if ($matrix[$i][$j] > $longestLength) { $longestLength = $matrix[$i][$j]; $longestIndexes = [$newIndex]; } elseif ($matrix[$i][$j] === $longestLength) { $longestIndexes[] = $newIndex; } } else { $matrix[$i][$j] = 0; } } } return $this->result($longestIndexes, $longestLength, $stringA); } /** * @param array> $matrix */ private function newIndex(array $matrix, int $i, int $j) : int { return $i - $matrix[$i][$j] + 1; } /** * @param list $longestIndexes * * @return string the extracted part of string or false on failure. */ private function result(array $longestIndexes, int $longestLength, string $stringA) : string { return $longestIndexes === [] ? '' : \substr($stringA, $longestIndexes[0], $longestLength); } }