827. Making A Large Island

Hard

50 Points

Array

Depth-First Search

Breadth-First Search

Union Find

Matrix

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.

Examples

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.