UVA821 floyd最短路+暴力

题意：给n条边，求每两个点之间的平均距离；

思路：数据是100条边，用floyd得到每两点之间的最短距离，然后遍历相加除以边的数目；

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cstdlib>
 5 #include <algorithm>
 6 #define N 110
 7 #define INF 0x7ffffff
 8 #define repu(i,a,b) for(int i=a;i<b;i++)
 9 using namespace std;
10 int p[N][N],vis[N][N];
11 int floyd(int n,int m)
12 {
13     repu(k,n,m)
14     {
15         repu(i,n,m)
16         repu(j,n,m)
17         if(p[i][k] < INF && p[k][j] < INF)
18         {
19             p[i][j] = min(p[i][j],p[i][k] + p[k][j]);
20         }
21     }
22 }
23 int main()
24 {
25     int u,v,kase=1;
26     while(1)
27     {
28         repu(i,0,N)
29         {
30             repu(j,0,N)
31             p[i][j] = INF,vis[i][j] = 0;
32             p[i][i] = 0;
33         }
34         memset(vis,0,sizeof(vis));
35         scanf("%d%d",&u,&v);
36         if(!u&&!v)
37             break;
38         p[u][v] = 1;
39         vis[u][v] = 1;
40         int minn = INF,maxn = 0;
41         while(1)
42         {
43             scanf("%d%d",&u,&v);
44             if(!u&&!v)
45                 break;
46             p[u][v] = 1;
47             if(!vis[u][v])
48                 vis[u][v] = 1;
49             maxn = max(max(v,u),maxn);
50             minn = min(min(v,u),minn);
51         }
52         int sum = 0,t = 0;
53         floyd(minn,maxn+1);
54         repu(i,minn,maxn+1)
55         {
56             repu(j,minn,maxn+1)
57             if(p[i][j]!=INF && i!=j )
58                 t++,sum += p[i][j];
59         }
60         double q = (double)sum / (double)t;
61        // cout<<t<<endl<<sum<<endl;
62         printf("Case %d: average length between pages = %.3lf clicks\n",kase++,q);
63     }
64     return 0;
65 }