use username split

criteria.py

@@ -37,10 +37,7 @@ def get_user_results(username: str) -> List[Dict]:
         List of user's quiz results
     """
     try:
-        ds = load_dataset(EXAM_DATASET_ID, split="train")
-
-        # Filter for this user's results
-        user_results = ds.filter(lambda x: x["username"] == username)
+        user_results = load_dataset(path=EXAM_DATASET_ID, split=username)
 
         results = user_results.to_list()
         print(f"Found {len(results)} results for user {username}")