7.14dfs例题：水洼数

 1 import java.util.Scanner;
 2 
 3 public class Seven_14dfs竞赛题水洼数 {
 4     private static int n;
 5     private static int m;
 6 
 7     public static void main(String[] args) {
 8         Scanner sc = new Scanner(System.in);
 9         n = sc.nextInt();
10         m = sc.nextInt();
11         char[][] a = new char[n][];
12         for (int i = 0; i < n; i++) {
13             a[i] = sc.next().toCharArray();
14         }
15         int cnt = 0;
16         for (int i = 0; i < n; i++) {
17             for (int j = 0; j < m; j++) {
18                 if (a[i][j] == ‘W‘) {
19                     dfs(a, i, j);// 清除一个水洼
20                     cnt++;
21                 }
22             }
23         }
24         System.out.println(cnt);
25     }
26 
27     private static void dfs(char[][] a, int i, int j) {
28         a[i][j] = ‘.‘;
29 
30         for (int k = -1; k < 2; k++) {// -1,0,1
31             for (int l = -1; l < 2; l++) {// -1,0,1
32                 if (k == 0 && l == 0)
33                     continue;
34 
35                 if (i + k >= 0 && i + k <= n - 1 && j + l >= 0
36                         && j + l <= m - 1) {
37                     if (a[i + k][j + l] == ‘W‘)
38                         dfs(a, i + k, j + l);
39                 }
40             }
41         }
42     }
43 
44 }