diff --git a/2024/day1/index.php b/2024/day1/index.php
index 25643ac..97cc9dc 100644
--- a/2024/day1/index.php
+++ b/2024/day1/index.php
@@ -51,9 +51,22 @@ function diffSum (array $list1, array $list2): int
 	return $sum;
 }
 
+function similarityScore (array $list1, array $list2): int
+{
+	$sum = 0;
+	foreach ($list1 as $search)
+	{
+		$rightList = array_filter($list2, fn (int $item) => $item === $search);
+		$sum += ($search * count($rightList));
+	}
+	
+	return $sum;
+}
+
 [$list1, $list2] = parseLists();
 
 $sumOfDifference = diffSum($list1, $list2);
+$similarityScore = similarityScore($list1, $list2);
 
 echo "Part 1: Total distance: $sumOfDifference\n";
-
+echo "Part 2: Similarity score: $similarityScore\n";
\ No newline at end of file