POJ 3259 Wormholes(判断负权回路|SPFA||Bellman-Ford)

//判断是否存在负权回路SPFA算法#include<iostream>#include<queue>#define MAXN 505#define MAXM 6000#define INF 1000000000using namespace std;int F,N,M,WW,m,u,v,w;int head[MAXN],V[MAXM],next[MAXM],W[MAXM];bool inq[MAXN];int cnt[MAXN],dis[MAXN];void addEdge(int u,int v,int w){V[m] = v;W[m] = w;next[m] = head[u];head[u] = m++;}void buildGraph(){scanf("%d%d%d",&N,&M,&WW);memset(head,-1,sizeof(head));m = 0;while(M--){scanf("%d%d%d",&u,&v,&w);addEdge(u,v,w);addEdge(v,u,w);}while(WW--){scanf("%d%d%d",&u,&v,&w);addEdge(u,v,-w);}}bool SPFA(){memset(cnt,0,sizeof(cnt));memset(inq,0,sizeof(inq));for(int i = 2;i <= N;++i)dis[i] = INF;//初始化DISdis[1] = 0;queue<int> q;q.push(1);inq[1] = 1;cnt[1]++;while(!q.empty()){int u = q.front();q.pop();inq[u] = 0;for(int e = head[u];e != -1;e = next[e]){if(dis[u] + W[e] < dis[V[e]]){dis[V[e]] = dis[u] + W[e];if(!inq[V[e]]){inq[V[e]] = 1;q.push(V[e]);if(++cnt[V[e]] > N)return 0;//入队次数超过结点数量，证明存在回路}}}}return 1;}int main(){scanf("%d",&F);while(F--){buildGraph();if(SPFA())printf("NO/n");else printf("YES/n");}return 0;}