delete pics to save space

1.4079.cpp

@@ -0,0 +1,49 @@
+#include<cstdio>
+#include<cstring>
+#include<cmath>
+#include<algorithm>
+using namespace std;
+const int maxn=1005;
+const int maxm=10005;
+struct Edge { int v; double t; Edge *next; };
+int T,n,m,kase;
+Edge mem[maxm*2],*G[maxn],*ecnt;
+inline void AddEdge(int u,int v,double t) { ecnt->v=v; ecnt->t=t; ecnt->next=G[u]; G[u]=ecnt++; } 
+bool vis[maxn]; double run[maxn];
+const double eps=1e-5;
+inline int sign(double x) { return fabs(x)<eps?0:(eps>0?1:-1); }
+int dfs(int u,double t)
+{
+	vis[u]=true; run[u]=t;
+	for(Edge *it=G[u];it;it=it->next)
+	{
+		int v=it->v;
+		if(!vis[v]) { if(dfs(v,t*it->t)) return 1; }
+		else if(sign(run[v]-t*it->t)) return 1;
+	}
+	return 0;
+}
+int main()
+{
+#ifdef local
+	freopen("pro.in","r",stdin);
+#endif
+	scanf("%d",&T);
+	while(T-->0)
+	{
+		scanf("%d%d",&n,&m);
+		memset(G,0,sizeof(G)); ecnt=mem;
+		while(m-->0)
+		{
+			int u,v; double x,y; scanf("%d%d%lf%lf",&u,&v,&x,&y);
+			AddEdge(u,v,y/x); AddEdge(v,u,x/y);
+		}
+		memset(vis,0,sizeof(vis));
+		int err=0;
+		for(int i=1;i<=n&&!err;i++)
+			if(!vis[i])
+				err|=dfs(i,1);
+		printf("Case #%d: %s\n",++kase,err?"No":"Yes");
+	}
+	return 0;
+}