题目

法1：DFS

最简单的DFS必须掌握！！！

class Solution {public int maxAreaOfIsland(int[][] grid) {int m = grid.length, n = grid[0].length, ans = 0;if (m == 0 || n == 0) {return ans;}boolean[][] visited = new boolean[m][n];for (int i = 0; i < m; ++i) {for (int j = 0; j < n; ++j) {if (grid[i][j] == 1 && !visited[i][j]) {ans = Math.max(ans, dfs(grid, visited, i, j));}}}return ans;}public int dfs(int[][] grid, boolean[][] visited, int i, int j) {if (i >= 0 && i < grid.length && j >= 0 && j < grid[0].length && grid[i][j] == 1 && !visited[i][j]) {visited[i][j] = true;return 1 + dfs(grid, visited, i - 1, j) + dfs(grid, visited, i + 1, j)+ dfs(grid, visited, i, j - 1)+ dfs(grid, visited, i, j + 1);  }return 0;}
}