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