Tarjan求桥和割点

//Tarjan 求桥和割点 
Tarjan(u,fa)
{
    DFN[u]=LoW[u]=++time;
    Cu=grey;
    for each e=(u,v)
    {
        Tarjan(v,u);
        if(Cv=white)
        {
            
            low[u]=min(low[u],low[v]);
        }else
        {
            low[u]=min(low[u],DFN[v]);
        }
    }
}