[POJ 1321] 棋盘问题(DFS)

 1 import java.util.Arrays;
 2 import java.util.Scanner;
 3 
 4 public class Main {
 5     static char [][]maze = new char [10][10];
 6     static int []vis = new int [10];
 7     static int n,m,cnt;
 8     public static void main(String[] args) {
 9         Scanner cin = new Scanner(System.in);
10         while(cin.hasNext()) {
11             Arrays.fill(vis,0);
12             n = cin.nextInt();
13             m = cin.nextInt();
14             if(m == -1 && n == -1)
15                 break;
16             cnt = 0;
17             for(int i = 1;i <= n;i++) {
18                 String s = cin.next();
19                 for(int j = 1;j <= n;j++) {
20                     maze[i][j] = s.charAt(j - 1);
21                 }
22             }
23             DFS(1,0);
24             System.out.println(cnt);
25         }
26     }
27 
28     private static void DFS(int row,int step) {
29         if(row > n + 1)
30             return ;
31         if(step == m) {
32             cnt++;
33             return ;
34         }
35         for(int i = 1;i <= n;i++) {
36             if(maze[row][i] == ‘#‘ && vis[i] == 0)
37             {
38                 vis[i] = 1;
39                 DFS(row + 1,step + 1);
40                 vis[i] = 0;
41             }
42         }
43         DFS(row + 1,step);
44     }
45 }