poj 1321（DFS)

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cmath>
 4 #include<cstring>
 5 #include<algorithm>
 6 #include<queue>
 7 #include<map>
 8 #include<set>
 9 #include<vector>
10 #include<cstdlib>
11 #include<string>
12 #define eps 0.000000001
13 typedef long long ll;
14 typedef unsigned long long LL;
15 using namespace std;
16 const int N=1000+10;
17 int visited[N];
18 char mp[N][100];
19 int num;
20 int n,k;
21 int _x[4]={0,1,0,-1};
22 int _y[4]={1,0,-1,0};
23 void DFS(int x,int y){
24     if(y==k){
25         num++;
26         return;
27     }
28     for(int i=x;i<n;i++)
29     for(int j=0;j<n;j++){
30        if(mp[i][j]==‘#‘&&visited[j]==0){
31             visited[j]=1;
32             DFS(i+1,y+1);
33             visited[j]=0;
34        }
35     }
36 }
37 int main(){
38     while(scanf("%d%d",&n,&k)!=EOF){
39         if(n==-1&&k==-1)break;
40         memset(visited,0,sizeof(visited));
41         for(int i=0;i<n;i++)scanf("%s",mp[i]);
42         num=0;
43         DFS(0,0);
44         cout<<num<<endl;
45     }
46 }