...少打了个括号，AC了
```
#include<bits/stdc++.h>
using namespace std;
int n,ans=0,lit[20],ed;
void dfs(int k,int a,int b,int c){
if(a==ed){++ans;return;}
for(register int i=ed&(~(a|b|c|lit[k]));i;i-=(i&-i)){
int x=i&-i;
dfs(k+1,a+x,(b+x)>>1,(c+x)<<1);
}
}
int main(){
std::ios::sync_with_stdio(false);
cin>>n;ed=(1<<n)-1;
string tmp;memset(lit,0,sizeof(lit));
for(register int i=1;i<=n;++i){
cin>>tmp;tmp=' '+tmp;
for(register int j=1;j<=n;++j)
tmp[j]=='.'?lit[i]|=(1<<(n-j)):0;
}
dfs(1,0,0,0);
cout<<ans<<endl;
return 0;
}
```
by LightString @ 2019-07-13 10:10:05
@[玉田小白](/space/show?uid=111048)
我这ti0分
------------
QAQ
by FOREIGN @ 2019-07-13 10:18:52
@[FOREIGN](/space/show?uid=200467) quq
by LightString @ 2019-07-13 11:02:48
@[玉田小白](/space/show?uid=111048)
emmmmmmmmmmmmmmmmmmmmmmmmmmmm
by FOREIGN @ 2019-07-13 11:10:59