> #include<cstdio>
> #include<cstdlib>
> #include<vector>
> #include<iostream>
> #include<cstring>
> #define N 505
> using namespace std;
> 
> int f,m,w,n,cnt,head[4*N],dist[N],q[N*10],num[N],map[N][N];
> bool vis[N];
> 
> bool SPFA(int begin,int end)
> {
> 	int h=-1,t=0;
> 	memset(vis,0,sizeof(vis));
> 	memset(num,0,sizeof(num));
> 	memset(dist,0x3f,sizeof(dist));
> 	q[0]=begin;vis[begin]=1;num[begin]++;
> 	dist[begin]=0;
> 	while(h<t)
> 	{
> 		int x=q[++h];
> 		for(int i=1;i<=n;i++)
> 		{
> 			if(dist[i]>dist[x]+map[x][i])
> 			{
> 				dist[i]=dist[x]+map[x][i];if(!vis[i])vis[i]=1,q[++t]=i,num[i]++;
> 			}
> 			if(num[i]>n)return true;
> 		}vis[x]=0;
> 	}
> 	return false;
> }
> 
> int main()
> {
> 	scanf("%d",&f);
> 	while(f--)
> 	{
> 		scanf("%d%d%d",&n,&m,&w);
> 		memset(map,0x3f,sizeof(map));
> 		for(int i=0;i<m;i++)
> 		{
> 			int x,y,z;
> 			scanf("%d%d%d",&x,&y,&z);
> 			map[x][y]=map[y][x]=min(map[x][y],z);
> 		}
> 		for(int i=0;i<w;i++)
> 		{
> 			int x,y,z;
> 			scanf("%d%d%d",&x,&y,&z);
> 			map[x][y]=min(map[x][y],-z);
> 		}
> 		printf(SPFA(1,2)?"YES\n":"NO\n");
> 	}
> }
> 一直WA。。