Combination sum fix and test cases (#10193)

* fixed_incorrect_test_combination_sum * reverting fn arg * ruff * Update combination_sum.py * Update combination_sum.py --------- Co-authored-by: Maxim Smolskiy <mithridatus@mail.ru>

Author: architmaheshwari99

backtracking/combination_sum.py

@@ -47,8 +47,18 @@ def combination_sum(candidates: list, target: int) -> list:
  >>> combination_sum([-8, 2.3, 0], 1)
  Traceback (most recent call last):
  ...
- RecursionError: maximum recursion depth exceeded
+ ValueError: All elements in candidates must be non-negative
+ >>> combination_sum([], 1)
+ Traceback (most recent call last):
+ ...
+ ValueError: Candidates list should not be empty
  """
+ if not candidates:
+ raise ValueError("Candidates list should not be empty")
+
+ if any(x < 0 for x in candidates):
+ raise ValueError("All elements in candidates must be non-negative")
+
  path = [] # type: list[int]
  answer = [] # type: list[int]
  backtrack(candidates, path, answer, target, 0)