Refactor find_common_items

Author: sheida-shab

Sprint-1/Python/find_common_items/find_common_items.py

@@ -1,21 +1,24 @@
-from typing import List, Sequence, TypeVar
+from typing import List,  TypeVar
 
 ItemType = TypeVar("ItemType")
 
+# Original version: O(n × m) due to nested loops
+# Refactored version: O(n + m) using a set for constant-time lookups
+# This is optimal and cannot be further reduced because all input
+# elements must be processed at least once.
+# use this link :https://www.w3schools.com/python/ref_set_intersection.asp
 
 def find_common_items(
-    first_sequence: Sequence[ItemType], second_sequence: Sequence[ItemType]
+    first_sequence, second_sequence
 ) -> List[ItemType]:
     """
     Find common items between two arrays.
 
-    Time Complexity:
-    Space Complexity:
-    Optimal time complexity:
+    Time Complexity:O(n + m)
+    Space Complexity:O(n + m)
+    Optimal time complexity:O(n + m)
     """
-    common_items: List[ItemType] = []
-    for i in first_sequence:
-        for j in second_sequence:
-            if i == j and i not in common_items:
-                common_items.append(i)
-    return common_items
+    second_set=set(second_sequence)
+    first_set=set(first_sequence)
+    common_set=first_set.intersection(second_set)
+    return list(common_set)