I spent way too long staring at the traversal logic trying to find some fancy structural issue.
First, clarify the maze-solving algorithm and the exact symptom (e.g., exponential time due to revisiting). Then, systematically trace the code to identify where visited cells are not being tracked or marked, and propose a fix using a visited set or in-place marking. Finally, discuss time/space complexity improvements and potential edge cases.
Pro tip: Demonstrate strong debugging skills by not just fixing the bug but also explaining how you would test the fix and prevent similar issues, such as adding a visited set from the start or using memoization.
Ask clarifying questions about the maze representation, the algorithm used (e.g., DFS, BFS), and the performance issue. Confirm that the function should visit each cell at most once.
Examine the code for missing or incorrect tracking of visited cells. Look for places where the algorithm might revisit cells, such as not marking cells as visited before recursion or not checking a visited set.
Add a visited set or modify the maze in-place to mark visited cells. Ensure the fix is applied consistently at the right points in the algorithm.
Discuss how the fix improves time complexity (e.g., from exponential to O(m*n)) and consider edge cases like empty mazes, start/end points, and cycles.
Suggest test cases to verify the fix, including small mazes, large mazes, and mazes with no solution. Mention how to measure performance improvement.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.