poj 2253 Frogger （dijkstra最短路）

 1 #include <stdio.h>
 2 #include <math.h>
 3 const int INF=1010101010;
 4 double map[1010][1010],node[1010],Min;
 5 int n,vis[1010];
 6 
 7 double Max(double a,double b)
 8 {
 9     return a>b?a:b;
10 }
11 
12 void dijkstra()
13 {
14     int i,j,k,m;
15     for (i=0; i<n; i++)
16     {
17         node[i]=map[0][i];
18         vis[i]=0;
19     }
20     vis[0]=1;
21     for (k=0; k<n; k++)
22     {
23         Min=INF;
24         m=-1;
25         for (i=1; i<n; i++)
26             if (!vis[i])
27             {
28                 if (Min>node[i])
29                 {
30                     Min=node[i];
31                     m=i;
32                 }
33             }
34         if (m==-1)
35             break;
36         vis[m]=1;
37         //tm=m;
38         for (i=0; i<n; i++)
39         {
40             if (!vis[i]&&Max(node[m],map[m][i])<node[i])
41                 node[i]=Max(node[m],map[m][i]);
42 
43         }
44     }
45 }
46 
47 int main ()
48 {
49     double a[210],b[210];
50     int count=0,i,j;
51     while (scanf("%d",&n),n)
52     {
53         for (i=0; i<n; i++)
54         {
55             scanf("%lf%lf",&a[i],&b[i]);
56         }
57         for (i=0; i<n; i++)
58         {
59             for (j=0; j<n; j++)
60             {
61                 map[i][j]=map[j][i]=(a[i]-a[j])*(a[i]-a[j])+(b[i]-b[j])*(b[i]-b[j]);
62 
63             }
64         }
65         dijkstra();
66         printf("Scenario #%d\n", ++count);
67         printf("Frog Distance = %.3f\n\n", sqrt(node[1]));
68     }
69     return 0;
70 }