final testing...

server/tasks/task_hard.py

@@ -515,9 +515,9 @@ def merge_intervals(intervals):
 """,
         "explanation_keywords": ["merged[-1][1]", "end", "start", "overlap", "last interval", "index 1 vs 0"],
         "test_cases": [
-            {"input": [[1, 3], [2, 6], [8, 10]], "expected": [[1, 6], [8, 10]]},
-            {"input": [[1, 4], [4, 5]], "expected": [[1, 5]]},
-            {"input": [[1, 2]], "expected": [[1, 2]]},
+            {"input": [[[1, 3], [2, 6], [8, 10]]], "expected": [[1, 6], [8, 10]]},
+            {"input": [[[1, 4], [4, 5]]], "expected": [[1, 5]]},
+            {"input": [[[1, 2]]], "expected": [[1, 2]]},
         ],
         "test_cases_description": "Merge intervals: compare start with merged[-1][1] (end), not [0] (start)",
     },
@@ -625,4 +625,4 @@ def get_task_by_id(task_id: str) -> dict:
     for t in HARD_TASKS:
         if t["task_id"] == task_id:
             return t.copy()
-    return random.choice(HARD_TASKS).copy()
+    return random.choice(HARD_TASKS).copy()

server/tasks/task_medium.py

@@ -93,9 +93,9 @@ def flatten(lists):
     return result
 """,
         "test_cases": [
-            {"input": [[1, 2], [3, 4]], "expected": [1, 2, 3, 4]},
-            {"input": [[1]], "expected": [1]},
-            {"input": [[], [5, 6]], "expected": [5, 6]},
+            {"input": [[[1, 2], [3, 4]]], "expected": [1, 2, 3, 4]},
+            {"input": [[[1]]], "expected": [1]},
+            {"input": [[[], [5, 6]]], "expected": [5, 6]},
         ],
         "test_cases_description": "Flattens nested lists correctly without slicing off first element",
     },
@@ -452,7 +452,7 @@ def find_pairs(nums, target):
 """,
         "test_cases": [
             {"input": [[2, 7, 11, 15], 9], "expected": [(2, 7)]},
-            {"input": [[1, 2, 3, 4], 5], "expected": [(1, 4), (2, 3)]},
+            {"input": [[1, 2, 3, 4], 5], "expected": [(2, 3), (1, 4)]},
             {"input": [[1, 2], 10], "expected": []},
         ],
         "test_cases_description": "Finds all pairs summing to target using complement = target - n",
@@ -504,4 +504,4 @@ def get_task_by_id(task_id: str) -> dict:
     for t in MEDIUM_TASKS:
         if t["task_id"] == task_id:
             return t.copy()
-    return random.choice(MEDIUM_TASKS).copy()
+    return random.choice(MEDIUM_TASKS).copy()