POJ. Wormholes

1.Problem
http://poj.org/problem?id=3259

2.Idea
Using Bellman-Ford algorithm to detect negative loop in the graph.

3.Source

 #define MAX_E 10004  
 #define MAX_V 2003  
 struct edge { int from, to, cost; } es[MAX_E];  
 int V, E;  
 int d[MAX_V];  
 bool find_negative_loop() //Bellman-Ford  
 {  
      memset(d, 0, sizeof d);  
      for (int i = 0; i < V; i++) {  
           for (int j = 0; j < E; j++) {  
                edge e = es[j];  
                if (d[e.to] > d[e.from] + e.cost) {  
                     d[e.to] = d[e.from] + e.cost;  
                     if (i == V - 1) return true;  
                }  
           }  
      }  
      return false;  
 }  
 int main()  
 {  
      int t;  
      int x, y, z, cnt = 0;  
      cin >> t;  
      while (t--) {  
           int n, m, w;  
           cin >> n >> m >> w;  
           V = n;  
           E = m * 2 + w;  
           cnt = 0;  
           for (int i = 0; i < m; i++) {  
                cin >> x >> y >> z;  
                x--; y--;  
                es[cnt].from = x;  
                es[cnt].to = y;  
                es[cnt].cost = z;  
                cnt++;  
                es[cnt].to = x;  
                es[cnt].from = y;  
                es[cnt].cost = z;  
                cnt++;  
           }  
           for (int i = 0; i < w; i++) {  
                cin >> x >> y >> z;  
                x--; y--;  
                es[cnt].from = x;  
                es[cnt].to = y;  
                es[cnt].cost = -z;  
                cnt++;  
           }  
           if (find_negative_loop()) cout << "YES" << endl;  
           else cout << "NO" << endl;  
      }  
      return 0;  
 }