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vendor/sebastian/diff/src/LCS/TimeEfficientLongestCommonSubsequenceImplementation.php

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+<?php
+/*
+ * This file is part of sebastian/diff.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace SebastianBergmann\Diff\LCS;
+
+/**
+ * Time-efficient implementation of longest common subsequence calculation.
+ */
+class TimeEfficientImplementation implements LongestCommonSubsequence
+{
+    /**
+     * Calculates the longest common subsequence of two arrays.
+     *
+     * @param array $from
+     * @param array $to
+     *
+     * @return array
+     */
+    public function calculate(array $from, array $to)
+    {
+        $common     = array();
+        $fromLength = \count($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;
+                $matrix[$o] = \max(
+                    $matrix[$o - 1],
+                    $matrix[$o - $width],
+                    $from[$i - 1] === $to[$j - 1] ? $matrix[$o - $width - 1] + 1 : 0
+                );
+            }
+        }
+
+        $i = $fromLength;
+        $j = $toLength;
+
+        while ($i > 0 && $j > 0) {
+            if ($from[$i - 1] === $to[$j - 1]) {
+                $common[] = $from[$i - 1];
+                --$i;
+                --$j;
+            } else {
+                $o = ($j * $width) + $i;
+
+                if ($matrix[$o - $width] > $matrix[$o - 1]) {
+                    --$j;
+                } else {
+                    --$i;
+                }
+            }
+        }
+
+        return \array_reverse($common);
+    }
+}