FB面经 Prepare: Largest Island-优快云博客

本文介绍了一个寻找二维矩阵中最大岛屿面积的算法实现。通过深度优先搜索(DFS)遍历矩阵，标记已访问过的陆地，并计算当前岛屿的面积，以此找到最大的岛屿。示例代码演示了如何使用该算法处理特定输入。

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Find largest island in a board

 1 package fb;
 2 
 3 public class LargestIsland {
 4     public int findLargestIsland(int[][] board) {
 5         if (board==null || board.length==0 || board[0].length==0) return 0;
 6         int m = board.length;
 7         int n = board[0].length;
 8         int maxArea = 0;
 9         for (int i=0; i<m; i++) {
10             for (int j=0; j<n; j++) {
11                 if (board[i][j] != 1) continue;
12                 int area = 0;
13                 area = dfs(board, i, j, m, n);
14                 maxArea = Math.max(maxArea, area);
15             }
16         }
17         return maxArea;
18     }
19     
20     
21     public int dfs(int[][] board, int i, int j, int m, int n) {
22         if (i<0 || i>=m || j<0 || j>=n || board[i][j]!=1) return 0;
23         int area = 1;
24         board[i][j] = 2;
25         area += dfs(board, i-1, j, m, n);
26         area += dfs(board, i+1, j, m, n);
27         area += dfs(board, i, j-1, m, n);
28         area += dfs(board, i, j+1, m, n);
29         return area;
30     }
31 
32     /**
33      * @param args
34      */
35     public static void main(String[] args) {
36         // TODO Auto-generated method stub
37         LargestIsland sol = new LargestIsland();
38         //int[][] arr = new int[][]{{1,0,0,0},{0,1,0,0},{0,0,1,1},{0,0,1,1}};
39         int[][] arr = new int[][]{{1,0,1},{0,1,0},{0,1,1}};
40         int res = sol.findLargestIsland(arr);
41         System.out.println(res);
42     }
43 
44 }