1 #include <iostream>
2 #include <cstdio>
3 #include <cstring>
4 #include <queue>
5 #include <vector>
6 #define maxn 60
7 using namespace std;
8 vector<int> v,next;
9 vector<double> w;
10 double d[maxn];
11 int first[maxn],inq[maxn],cnt[maxn];
12 int n,m,e,ub;
13
14 void init()
15 {
16 ub = 0;
17 e = 0;
18 v.clear();
19 w.clear();
20 next.clear();
21 memset(first,-1,sizeof(first));
22 }
23
24 void Read_Graph()
25 {
26 int i,a,b,c;
27 for(i = 0;i < m;i++)
28 {
29 scanf("%d%d%d",&a,&b,&c);
30 ub = max(ub,c);
31 w.push_back(c);
32 v.push_back(b);
33 next.push_back(first[a]);
34 first[a] = e;
35 e++;
36 }
37 }
38
39 bool negativeCycle()
40 {
41 queue<int> q;
42 memset(cnt,0,sizeof(cnt));
43 memset(inq,0,sizeof(inq));
44 int i;
45 for(i = 1;i <= n;i++)
46 {
47 q.push(i);
48 d[i] = 0;
49 }
50 inq[1] = 1;
51 while(!q.empty())
52 {
53 int ith = q.front();
54 q.pop();
55 inq[ith] = 0;
56 for(i = first[ith];i != -1;i = next[i])
57 {
58 if(d[v[i]] > d[ith] + w[i])
59 {
60 d[v[i]] = d[ith] + w[i];
61 if(!inq[v[i]])
62 {
63 q.push(v[i]);
64 inq[v[i]] = 1;
65 if(++cnt[v[i]] > n) return true;
66 }
67 }
68 }
69 }
70 return false;
71 }
72
73 bool test(double x)
74 {
75 int i;
76 bool ret;
77 for(i = 0;i < e;i++)
78 w[i] -= x;
79 ret = negativeCycle();
80 for(i = 0;i < e;i++)
81 w[i] += x;
82 return ret;
83 }
84
85 int main()
86 {
87 int N;
88 scanf("%d",&N);
89 for(int ncase = 1;ncase <= N;ncase++)
90 {
91 scanf("%d%d",&n,&m);
92 init();
93 Read_Graph();
94 double middle,left = 0,right = ub;
95 if(!test(ub + 1))
96 {
97 printf("Case #%d: No cycle found.\n",ncase);
98 continue;
99 }
100 while(right - left > 1e-3)
101 {
102 middle = left + (right - left) / 2;
103 if(test(middle)) right = middle;
104 else left = middle;
105 }
106 printf("Case #%d: %.2f\n",ncase,left);
107 }
108 return 0;
109 }
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