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Yes, variations of grid traversal and island-shape problems frequently appear in FAANG-style interviews. They test knowledge of DFS/BFS, hashing, and pattern normalization within matrices.
A hash set is commonly used to store unique island shape signatures. During traversal, DFS or BFS helps collect relative positions of cells, which are then converted into a normalized representation and inserted into the set.
The optimal approach uses DFS or BFS to traverse each island and record its shape using relative coordinates from the starting cell. These coordinates are stored as a signature in a hash set to track unique island patterns. This ensures identical shapes are counted only once.
Relative coordinates normalize the island shape by anchoring it to the starting cell. This removes the effect of absolute grid position, allowing islands with identical shapes but different locations to be recognized as the same.
