1 #include<iostream> 2 #include<cstdio> 3 #include<string> 4 #include<vector> 5 #include<cstring> 6 using namespace std; 7 struct node 8 { 9     int x;10     int y;11 };12 int n, k, l, ans;13 bool w[10], h[10];14 vector<node>dot;15 void bfs(int a, int b)16 {17     if(a==k+1)18     {19         ans++;20         return;21     }22     for(int i = b; i < l; i++)23     {24         if(w[dot[i].x] || h[dot[i].y])    continue;25         else26         {27             w[dot[i].x] = h[dot[i].y] = true;28             bfs(a+1, i+1);29             w[dot[i].x] = h[dot[i].y] = false;30         }31     }32     return;33 }34 int main()35 {36 //    freopen("in.in","r",stdin);37     string c;38     node tmp;39     while(cin>>n>>k)40     {41         dot.clear();42         memset(w,0,sizeof(w));43         memset(h,0,sizeof(h));44         if(n==-1)    break;45         for(int i = 1; i <= n; i++)46         {47             cin>>c;48             for(int j = 1; j <= n; j++)49             {50                 51                 if(c[j-1]==‘#‘)52                 {53                     tmp.x = i;54                     tmp.y = j;55                     dot.push_back(tmp);56                 }57             }            58         }59 60         l = dot.size();61         ans = 0;62         bfs(1,0);63         cout<<ans<<endl;64     }65     return 0;66 }