Floyd求最小环
http://acm.hdu.edu.cn/showproblem.php?pid=1599
1 Problem : 1599 ( find the mincost route ) Judge Status : Accepted
2 RunId : 10374468 Language : C++ Author : l1285556798
3 Code Render Status : Rendered By HDOJ C++ Code Render Version 0.01 Beta
4
5 #include<stdio.h>
6 #define INF 0xffffff
7 int map[301][301],dist[301][301];
8 int n,m,ans;
9 void floyd()
10 {
11 for(int i=1;i<=n;i++)
12 for(int j=1;j<=n;j++)
13 dist[i][j]=map[i][j];
14 for(int k=1;k<=n;k++)
15 {
16 for(int i=1;i<=n;i++)
17 {
18 for(int j=1;j<=n;j++)
19 {
20 if(i!=j&&j!=k&&k!=i&&dist[i][j]!=INF&&map[j][k]!=INF&&map[k][i]!=INF&&dist[i][j]+map[j][k]+map[k][i]<ans)
21 ans=dist[i][j]+map[j][k]+map[k][i];
22 }
23 }
24 for(int i=1;i<=n;i++)
25 {
26 for(int j=1;j<=n;j++)
27 {
28 if(dist[i][k]!=INF&&dist[k][j]!=INF&&dist[i][k]+dist[k][j]<dist[i][j])
29 dist[i][j]=dist[i][k]+dist[k][j]; //注意取不同点
30 }
31 }
32 }
33 }
34 int main()
35 {
36 while(scanf("%d%d",&n,&m)!=EOF)
37 {
38 for(int i=1;i<=n;i++)
39 for(int j=1;j<=n;j++)
40 {
41 if(i!=j)
42 map[i][j]=INF;
43 else
44 map[i][j]=0;
45 }
46 int a,b,c;
47 for(int i=0;i<m;i++)
48 {
49 scanf("%d%d%d",&a,&b,&c);
50 if(a!=b&&c<map[a][b])
51 map[a][b]=map[b][a]=c;
52 }
53 ans=INF;
54 floyd();
55 if(ans==INF)
56 printf("It's impossible.\n");
57 else
58 printf("%d\n",ans);
59 }
60 return 0;
61 }
