0827. Making A Large Island

https://leetcode.com/problems/making-a-large-island

Description

You are given an n x n binary matrix grid. You are allowed to change at most one 0 to be 1.

Return the size of the largest island in grid after applying this operation.

An island is a 4-directionally connected group of 1s.

Example 1:

**Input:** grid = [[1,0],[0,1]]
**Output:** 3
**Explanation:** Change one 0 to 1 and connect two 1s, then we get an island with area = 3.

Example 2:

**Input:** grid = [[1,1],[1,0]]
**Output:** 4
**Explanation:** Change the 0 to 1 and make the island bigger, only one island with area = 4.

Example 3:

**Input:** grid = [[1,1],[1,1]]
**Output:** 4
**Explanation:** Can't change any 0 to 1, only one island with area = 4.

Constraints:

• n == grid.length

• n == grid[i].length

• 1 <= n <= 500

• grid[i][j] is either 0 or 1.

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