<?php declare(strict_types=1);
namespace SebastianBergmann\Diff;
use function array_reverse;
use function count;
use function max;
use SplFixedArray;
final class TimeEfficientLongestCommonSubsequenceCalculator implements LongestCommonSubsequenceCalculator
{
public function calculate(array $from, array $to): array
{
$common = [];
$fromLength = count($from);
$toLength = count($to);
$width = $fromLength + 1;
$matrix = new SplFixedArray($width * ($toLength + 1));
for ($i = 0; $i <= $fromLength; $i++) {
$matrix[$i] = 0;
}
for ($j = 0; $j <= $toLength; $j++) {
$matrix[$j * $width] = 0;
}
for ($i = 1; $i <= $fromLength; $i++) {
for ($j = 1; $j <= $toLength; $j++) {
$o = ($j * $width) + $i;
$firstOrLast = $from[$i - 1] === $to[$j - 1] ? $matrix[$o - $width - 1] + 1 : 0;
if ($matrix[$o - 1] > $matrix[$o - $width]) {