poj 1321

dfs

#include<iostream>#include<cstring>#include<algorithm>using namespace std;char chess[10][10];int col[10];int n,m,ans;void dfs(int row,int num){int i,j;if(num==m){ans++;return;}for(i=row+1;i<=n;i++)for(j=1;j<=n;j++)if(chess[i][j]!='.' && !col[j]){col[j]=1;dfs(i,num+1);col[j]=0;}}int main(){int i;while(cin>>n>>m){ans=0;if(n==-1 && m==-1)break;memset(col,0,sizeof(col));for(i=1;i<=n;i++)cin>>chess[i]+1;dfs(0,0);cout<<ans<<endl;}return 0;}