洛古——P1433 吃奶酪

 1 #include <algorithm>
 2 #include <cstdio>
 3 #include <cmath>
 4 
 5 using namespace std;
 6 
 7 int n,vis[20];
 8 struct Node
 9 {
10     double x,y;
11 }node[20];
12 double ans=1<<30,dis[20][20];
13 
14 void DFS(int now,double dist,int cnt)
15 {
16     if(dist>=ans) return;
17     if(cnt==n+1)
18     {
19         if(ans>dist) ans=dist;
20         return ;
21     }
22     for(int i=1;i<=n;i++)
23     {
24         if(vis[i]) continue;
25         vis[i]=1;
26         DFS(i,dist+dis[now][i],cnt+1);
27         vis[i]=0;
28     }
29 }
30 
31 int main()
32 {
33     scanf("%d",&n);
34     for(int i=1;i<=n;i++)
35         scanf("%lf%lf",&node[i].x,&node[i].y);
36     for(int i=0;i<=n;i++)
37         for(int j=0;j<=n;j++)
38             dis[i][j]=sqrt((node[i].x-node[j].x)*(node[i].x-node[j].x)+(node[i].y-node[j].y)*(node[i].y-node[j].y));
39     DFS(0,0,1);
40     printf("%.2lf",ans);
41     return 0;
42 }