How should I practice Count Four-Neighbor Islands?

Start by reading the full statement, solve the visible examples, then compare the pattern against related NVIDIA phone screen problems in FastPrep.

Is Count Four-Neighbor Islands associated with NVIDIA?

FastPrep tags this as a NVIDIA phone screen coding practice problem when the problem catalog has that company and stage context.

Count Four-Neighbor Islands

NVIDIA● MediumNEW GRADPHONE SCREEN

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Problem statement

Given a rectangular grid of 0 (water) and 1 (land), count its islands.

For this practice, land cells belong to the same island when connected through their top, bottom, left, or right sides. Diagonally touching cells are separate unless a path of side-connected land joins them. Each land cell belongs to exactly one island. Return 0 for an empty grid.

Function

numIslands(grid: int[][]) → int

Examples

Example 1

grid = [[1,1,0],[0,1,0],[0,0,1]]return = 2

The three connected upper-left land cells form one island, and the lower-right cell forms another.

Example 2

grid = [[1,0],[0,1]]return = 2

The two land cells meet only diagonally, so they form two islands.

Example 3

grid = []return = 0

There are no land cells in an empty grid.

Constraints

0 <= grid.length <= 50.
When the grid is nonempty, every row has the same length between 1 and 50.
Every cell is 0 or 1.
The input grid need not be modified.