Count Islands on Infinite Grid | Dataford Interview Questions

Infinitely large grid of water; cells can be converted to land at any time; answer repeated queries of how many islands there are

Asked in the Round 1 stage. Treat cells as connected only through their four direct neighbors. A query asks for the island count after a specified operation has been applied.

Output

One row per query, with query_id, operation_id, and island_count
Include queries in ascending query_id order
Count each connected land component once, and return zero when no land exists

Schema

grid_operations

Column	Type	Description
operation_idPK	INT	Sequential land-conversion operation identifier
row_coord	INT	Row coordinate of the converted cell
col_coord	INT	Column coordinate of the converted cell
operation_note	VARCHAR(100)	Optional note about the operation

island_queries

Column	Type	Description
query_idPK	INT	Identifier for the repeated query
operation_id	INT	Operation state at which the island count is requested
query_label	VARCHAR(100)	Optional label for the query

Your question is Count Islands on Infinite Grid. Start with the requirements and the two tables in the Question tab.

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