POJ 3259

 1 #include<iostream>
 2 #include<cstring>
 3 using namespace std;
 4 
 5 #define MAX_V 6565
 6 
 7 struct edge
 8 {
 9     int from,to,cost;
10     //有需要edge的数组时要加上这个无参构造函数
11     edge(){}
12     edge(int from,int to,int cost)
13     {
14         this->from=from;
15         this->to=to;
16         this->cost=cost;
17     }
18 };
19 
20 edge es[MAX_V];
21 int V,E;
22 int d[MAX_V];
23 
24 bool find_negative_loop()
25 {
26     //找负圈要加
27     memset(d,0,sizeof(d));
28     for(int k=0;k<V;k++)
29     {
30         for(int i=0;i<E;i++)
31         {
32             edge e=es[i];
33             if(d[e.to]>d[e.from]+e.cost)
34             {
35                 d[e.to]=d[e.from]+e.cost;
36                 if(k==V-1)
37                 {
38                     return true;
39                 }
40             }
41         }
42     }
43     return false;
44 }
45 
46 int main()
47 {
48     int T;
49     cin>>T;
50     while(T--)
51     {
52         int M,W;
53         cin>>V>>M>>W;
54         E=0;
55         //注意无向图要重复一遍
56         for(int i=0;i<M;i++)
57         {
58             int from,to,cost;
59             cin>>from>>to>>cost;
60             from--;
61             to--;
62             es[E].from=from;
63             es[E].to=to;
64             es[E].cost=cost;
65             E++;
66             es[E].from=to;
67             es[E].to=from;
68             es[E].cost=cost;
69             E++;
70         }
71         for(int i=0;i<W;i++)
72         {
73             int from,to,cost;
74             cin>>from>>to>>cost;
75             from--;
76             to--;
77             es[E].from=from;
78             es[E].to=to;
79             es[E].cost=-cost;
80             E++;
81         }
82         if(find_negative_loop())
83         {
84             cout<<"YES"<<endl;
85         }
86         else
87         {
88             cout<<"NO"<<endl;
89         }
90     }
91     return 0;
92 }