hdu 1599 find the mincost route 最小环

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<cstdlib>
 5 #include<cmath>
 6 #include<algorithm>
 7 #define inf 0x7fffffff
 8 using namespace std;
 9 const int maxn=100+10;
10 
11 int n,m;
12 int dist[maxn][maxn],edge[maxn][maxn];
13 
14 void floyd()
15 {
16     int ans=1000100;
17     for (int i=1 ;i<=n ;i++)
18     {
19         for (int j=1 ;j<=n ;j++)
20             dist[i][j]=edge[i][j];
21     }
22     for (int k=1 ;k<=n ;k++)
23     {
24         for (int i=1 ;i<k ;i++)
25         {
26             for (int j=i+1 ;j<k ;j++)
27             {
28                 if (dist[j][i]+edge[i][k]+edge[k][j]<1000100)
29                     ans=min(ans,dist[j][i]+edge[i][k]+edge[k][j]);
30             }
31         }
32         for (int i=1 ;i<=n ;i++)
33         {
34             for (int j=1 ;j<=n ;j++)
35             {
36                 if (dist[i][j]>dist[i][k]+dist[k][j])
37                     dist[i][j]=dist[i][k]+dist[k][j];
38             }
39         }
40     }
41     if (ans==1000100) printf("It‘s impossible.\n");
42     else printf("%d\n",ans);
43 }
44 
45 int main()
46 {
47     while (scanf("%d%d",&n,&m)!=EOF)
48     {
49         for (int i=1 ;i<=n ;i++)
50         {
51             for (int j=1 ;j<=n ;j++)
52                 edge[i][j]=1000100;
53             edge[i][i]=0;
54         }
55         int x,y,cost;
56         for (int i=0 ;i<m ;i++)
57         {
58             scanf("%d%d%d",&x,&y,&cost);
59             if (edge[x][y]>cost) edge[x][y]=edge[y][x]=cost;
60         }
61         floyd();
62     }
63     return 0;
64 }