diff --git a/LeetCode/187.py b/LeetCode/187.py
new file mode 100644
index 0000000..c7da0d7
--- /dev/null
+++ b/LeetCode/187.py
@@ -0,0 +1,11 @@
+class Solution:
+    def findRepeatedDnaSequences(self, s: str) -> List[str]:
+        seen = set()
+        results = set()
+        for i in range(len(s) - 9):
+            pattern = s[i:i+10]
+            if pattern not in seen:
+                seen.add(pattern)
+            else:
+                results.add(pattern)
+        return list(results)