给你一个由 1（陆地）和 0（水）组成的的二维网格，请你计算网格中岛屿的数量。
岛屿总是被水包围，并且每座岛屿只能由水平方向和/或竖直方向上相邻的陆地连接形成。
此外，你可以假设该网格的四条边均被水包围。
示例 1：
输入：grid = [ ["1","1","1","1","0"], ["1","1","0","1","0"], ["1","1","0","0","0"], ["0","0","0","0","0"] ] 输出：1
示例 2：
输入：grid = [ ["1","1","0","0","0"], ["1","1","0","0","0"], ["0","0","1","0","0"], ["0","0","0","1","1"] ] 输出：3
提示：
-
m == grid.length -
n == grid[i].length -
1 <= m, n <= 300 -
grid[i][j]的值为0或1
思考题：看题解可以使用 UnionFind 来解决这个问题。可以思考一下，如何实现？
这道题与 0130-surrounded-regions.adoc 类似。
- 一刷
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link:{sourcedir}/_0200_NumberOfIslands.java[role=include] - 二刷
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link:{sourcedir}/_0200_NumberOfIslands_2.java[role=include] - 三刷
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link:{sourcedir}/_0200_NumberOfIslands_3.java[role=include]