Strengths:

• The solution correctly implements the backtracking approach to solve the problem.
• The code is clean, well-structured, and easy to understand.
• The use of comments to explain the logic is commendable.
• The solution is more space-efficient than the reference solution due to the use of backtracking.

Areas for Improvement:

• While the time complexity is comparable, it would be beneficial to explain why the time complexity is O(2^(m+n)) in more detail, especially considering the recursive nature of the solution.
• The variable name pivot could be renamed to index or start for better clarity, as pivot might not immediately convey its purpose to all readers.