1 //纯dfs()
2
3 #include <iostream>
4 #include <algorithm>
5 #include <string>
6 #include <cstdio>
7 #include <cstring>
8
9 using namespace std;
10 const int maxn = 10;
11 char g[maxn][maxn];
12 bool vis[maxn]; //列标记
13 int n, k;
14 int ans;
15
16 void dfs(int nowx,int num){
17 if (num == k){
18 ans++;
19 return;
20 }
21
22 if (nowx >= n) //越界
23 return;
24
25 for (int i = 0; i < n; i++){
26 if (g[nowx][i] == '#' && !vis[i]){
27 vis[i] = 1;
28 dfs(nowx + 1, num + 1);
29 vis[i] = 0;
30 }
31 }
32 dfs(nowx + 1, num);
33 return;
34 }
35
36 int main(){
37 while (~scanf("%d %d", &n, &k)){
38 if (n == -1 && k == -1)
39 break;
40 ans = 0;
41 memset(vis, 0, sizeof(vis));
42 for (int i = 0; i < n; i++){
43 scanf("%s", &g[i]);
44 }
45 dfs(0, 0);
46 printf("%d\n", ans);
47 }
48 //system("pause");
49 return 0;
50 }
