How should I practice Largest Island After One Land Conversion?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Google onsite interview problems in FastPrep.

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Largest Island After One Land Conversion

Google● HardNEW GRADONSITE INTERVIEW

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Problem statement

You are given an n x n binary matrix grid. You may change at most one 0 into 1.

An island is a four-directionally connected group of 1s. Return the largest island area obtainable after the optional conversion.

Function

largestIsland(grid: int[][]) → int

Examples

Example 1

grid = [[1,0],[0,1]]return = 3

Changing either zero joins the two diagonal land cells through the converted cell.

Example 2

grid = [[1,1],[1,0]]return = 4

Changing the only zero makes the whole grid one island.

Example 3

grid = [[1,1],[1,1]]return = 4

The grid is already one island, so no conversion is needed.

Constraints

1 <= n <= 500.
n == grid.length == grid[i].length.
grid[i][j] is 0 or 1.
Four-directional adjacency defines an island.