棋盘问题--POJ 1321

#include<iostream>
using namespace std;

int n,k,num,ans;
bool map[9][9],col[9];

void DFS(int k)
{
int i;
if(k==0)
{
ans++;
return;
}
if(num>=n)
return;
if(k>(n-num))
return;
num++;
for(i=1;i<=n;i++)
{
if(!map[num][i])
continue;
if(col[i])
continue;
col[i]=1;
DFS(k-1);
col[i]=0;
}
DFS(k);
num--;
return;
}

int main()
{
char ch;
int i;
while(cin>>n>>k)
{
if(n==-1&&k==-1)
break;
memset(map,0,sizeof(map));
memset(col,0,sizeof(col));
ans=0;
for(i=1;i<=n;i++)
for(int j=1;j<=n;j++)
{
cin>>ch;
if(ch=='#')
map[i][j]=1;
}
for(i=1;i<=n;i++)
{
num=1;
if(!map[num][i])
continue;
if(col[i])
continue;
col[i]=1;
DFS(k-1);
col[i]=0;
}
DFS(k);
cout<<ans<<endl;
}
return 0;
}