Grid/Graph BFS Problem from 1point3acres Link (expects possible O(1) query with preprocessing)

Problem: From 1point3acres link (insufficient details) Source link: https://www.1point3acres.com/bbs/thread-1091211-1-1.html From the interview notes: A standard BFS solution was implemented. The interviewer kept pushing for O(1). Union-Find and bidirectional BFS were not accepted. The graph edges seem to be defined such that any nodes in the same row/column are reachable in 1 step. Because the full statement is not included in the experience text, we keep the link only to avoid inventing missing details.