The diagonal constraint is what trips you up at first.
Clarify the problem constraints and edge cases, then propose an efficient algorithm using spatial indexing (e.g., sorting by x+y and x-y) to quickly find the nearest unvisited server along each diagonal. Simulate the traversal step-by-step, updating visited servers and handling skips, and finally return the last visited server's coordinates.
Pro tip: Demonstrate awareness of real-world scalability by discussing how to handle large n and many redirects, and mention potential optimizations like balanced trees or hash maps for diagonal groups.
Ask about input format, constraints (n, number of redirects), and edge cases such as no unvisited server in a direction or multiple servers at the same distance.
Group servers by their diagonal lines (x+y for NE/SW, x-y for NW/SE) and sort each group to enable binary search for the nearest unvisited server.
Start at the first server, mark it visited, and for each redirect, find the nearest unvisited server in the specified direction; if none, skip the step.
Discuss time and space complexity, and propose optimizations like using balanced BSTs or lazy deletion to handle visited servers efficiently.
After processing all redirects, return the coordinates of the last visited server, and walk through a small example to verify correctness.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.