poj2253

 1 //prim 改
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 const int MAXN = 205;
 6 const int inf = 100000000;
 7 int x[MAXN];
 8 int y[MAXN];
 9 double a[MAXN][MAXN];
10 bool vis[MAXN];
11 double dis[MAXN];
12 int n;
13 double max(double a,double b)
14 {
15     return a>b?a:b;
16 }
17 void pre()
18 {
19     for (int i=0;i<n;i++)
20     {
21         for (int j=0;j<n;j++)
22         {
23            a[i][j]=sqrt((double )(x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]));
24         }
25     }
26 }
27 double prim(int src,int end)
28 {
29     double ans;
30     memset(vis,0,sizeof(vis));
31     for (int i=0;i<n;i++)
32     dis[i]=(double )inf;
33     dis[src]=0;
34     for (int i=0;i<n;i++)
35     {
36         double temp=(double )inf;
37         int k;
38         for (int j=0;j<n;j++)
39         {
40             if (vis[j]) continue;
41             if (temp>dis[j])
42             {
43                 temp=dis[j];
44                 k=j;
45             }
46         }
47         ans=max(ans,temp);
48         if (k==end) return ans;
49         vis[k]=1;
50         for (int j=0;j<n;j++)
51         {
52             if (vis[j]) continue;
53             if (dis[j]>a[k][j])
54             dis[j]=a[k][j];
55         }
56     }
57     return ans;
58 }
59 int main()
60 {
61     int t=0;
62     while (scanf("%d",&n),n)
63     {
64         for (int i=0;i<n;i++)
65         {
66             scanf("%d%d",&x[i],&y[i]);
67         }
68         pre();
69         double ans=prim(0,1);
70 
71         printf("Scenario #%d\n",++t);
72         printf("Frog Distance = %.3f\n\n",ans);
73     }
74     return 0;
75 }