Just variant question to leetcode- 200;

Use simple DFS solution and int[] to count area.

```
class Solution {
public int maxAreaOfIsland(int[][] grid) {
int res = 0;
if (grid == null || grid.length == 0 || grid[0].length == 0) return 0;
for (int i = 0; i < grid.length; i++) {
for (int j = 0; j < grid[0].length; j++) {
if(grid[i][j] == 1) {
int[] count = new int[1];
dfs(grid, count, i, j);
res = Math.max(res, count[0]);
}
}
}
return res;
}
private void dfs(int[][] grid, int[] count, int x, int y) {
if (x < 0 || x >= grid.length || y < 0 || y >= grid[0].length || grid[x][y] == 0) return;
grid[x][y] = 0;
count[0]++;
dfs(grid, count, x - 1, y);
dfs(grid, count, x + 1, y);
dfs(grid, count, x, y - 1);
dfs(grid, count, x, y + 1);
}
}
```