@[judgejudge](/space/show?uid=133986) 不加优化的DFS复杂度也是n!，最优性剪枝后就快多了
```
inline void DFS(int x,int tot,double dis){
if(dis>ans)return;
if(tot==n+1){
ans=min(ans,dis);
return;
}
for(int i=1;i<=n;i++)
if(!vst[i]){
vst[i]=1;
DFS(i,tot+1,dis+cal(x,i));
vst[i]=0;
}
}
```
by Soledad_S @ 2019-03-05 22:30:39