827. Making A Large Island

Description

In a 2D grid of 0s and 1s, we change at most one 0 to a 1.

After, what is the size of the largest island? (An island is a 4-directionally connected group of 1s).

Example 1:

Input: [[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: [[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: [[1, 1], [1, 1]]

Output: 4

Explanation: Can't change any 0 to 1, only one island with area = 4.

Notes:

<li><code>1 &lt;= grid.length = grid[0].length &lt;= 50</code>.</li>

<li><code>0 &lt;= grid[i][j] &lt;= 1</code>.</li>