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diff --git a/vendor/caxy/php-htmldiff/lib/Caxy/HtmlDiff/LcsService.php b/vendor/caxy/php-htmldiff/lib/Caxy/HtmlDiff/LcsService.php
new file mode 100644
index 000000000..6de37273b
--- /dev/null
+++ b/vendor/caxy/php-htmldiff/lib/Caxy/HtmlDiff/LcsService.php
@@ -0,0 +1,88 @@
+<?php
+
+namespace Caxy\HtmlDiff;
+
+use Caxy\HtmlDiff\Strategy\EqualMatchStrategy;
+use Caxy\HtmlDiff\Strategy\MatchStrategyInterface;
+
+class LcsService
+{
+    /**
+     * @var MatchStrategyInterface
+     */
+    protected $matchStrategy;
+
+    /**
+     * LcsService constructor.
+     *
+     * @param MatchStrategyInterface $matchStrategy
+     */
+    public function __construct(MatchStrategyInterface $matchStrategy = null)
+    {
+        if (null === $matchStrategy) {
+            $matchStrategy = new EqualMatchStrategy();
+        }
+
+        $this->matchStrategy = $matchStrategy;
+    }
+
+    /**
+     * @param array $a
+     * @param array $b
+     *
+     * @return array
+     */
+    public function longestCommonSubsequence(array $a, array $b)
+    {
+        $c = array();
+
+        $m = count($a);
+        $n = count($b);
+
+        for ($i = 0; $i <= $m; $i++) {
+            $c[$i][0] = 0;
+        }
+
+        for ($j = 0; $j <= $n; $j++) {
+            $c[0][$j] = 0;
+        }
+
+        for ($i = 1; $i <= $m; $i++) {
+            for ($j = 1; $j <= $n; $j++) {
+                if ($this->matchStrategy->isMatch($a[$i - 1], $b[$j - 1])) {
+                    $c[$i][$j] = 1 + (isset($c[$i - 1][$j - 1]) ? $c[$i - 1][$j - 1] : 0);
+                } else {
+                    $c[$i][$j] = max(
+                        isset($c[$i][$j - 1]) ? $c[$i][$j - 1] : 0,
+                        isset($c[$i - 1][$j]) ? $c[$i - 1][$j] : 0
+                    );
+                }
+            }
+        }
+
+        $lcs = array_pad(array(), $m + 1, 0);
+        $this->compileMatches($c, $a, $b, $m, $n, $lcs);
+
+        return $lcs;
+    }
+
+    /**
+     * @param $c
+     * @param $a
+     * @param $b
+     * @param $i
+     * @param $j
+     * @param $matches
+     */
+    protected function compileMatches($c, $a, $b, $i, $j, &$matches)
+    {
+        if ($i > 0 && $j > 0 && $this->matchStrategy->isMatch($a[$i - 1], $b[$j - 1])) {
+            $this->compileMatches($c, $a, $b, $i - 1, $j - 1, $matches);
+            $matches[$i] = $j;
+        } elseif ($j > 0 && ($i === 0 || $c[$i][$j - 1] >= $c[$i - 1][$j])) {
+            $this->compileMatches($c, $a, $b, $i, $j - 1, $matches);
+        } elseif ($i > 0 && ($j === 0 || $c[$i][$j - 1] < $c[$i - 1][$j])) {
+            $this->compileMatches($c, $a, $b, $i - 1, $j, $matches);
+        }
+    }
+}