tarjan模板

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//************************************************************
void v_dcc_tarjan(int x)  //无向图->点双联通分量(找割点)
{
    low[x]=dfn[x]=++indx;
    int flag=0;
    for(Reg int i=fir[x];i;i=lian[i].next)
    {
        if(!dfn[lian[i].ed])
        {
            v_dcc_tarjan(lian[i].ed);
            low[x]=min(low[x],low[lian[i].ed]);
            if(low[lian[i].ed]>=dfn[x])
            {
                ++flag;
                if(x!=root||flag>1) cur[x]=1;
            }
        }
        else low[x]=min(low[x],dfn[lian[i].ed]);
    }
    return;
}
//************************************************************
void v_dcc_tarjan(int x)  //无向图->点双联通分量(找点双联通)
{
    low[x]=dfn[x]=++indx;
    stack[++stack[0]]=x;
    int flag=0;
    if(x==root&&!fir[x]) v_dcc[++cnt].push_back(x);
    else for(Reg int i=fir[x];i;i=lian[i].next)
    {
        if(!dfn[lian[i].ed])
        {
            v_dcc_tarjan(lian[i].ed);
            low[x]=min(low[x],low[lian[i].ed]);
            if(low[lian[i].ed]>=dfn[x])
            {
                ++flag; if(x!=root||flag>1) cur[x]=1;
                ++cnt;
                while(stack[stack[0]]!=lian[i].ed)
                    v_dcc[cnt].push_back(stack[stack[0]--]);
                v_dcc[cnt].push_back(stack[stack[0]--]);
                v_dcc[cnt].push_back(x);
            }
        }
        else low[x]=min(low[x],dfn[lian[i].ed]);
    }
    return;
}
void v_dcc_union()  //无向图->点双联通分量(缩点)
{
    int num=cnt;
    for(Reg int i=1;i<=n;++i) if(cur[i]) pos[i]=++num;
    for(Reg int i=1;i<=cnt;++i)
    {
        for(Reg int j=0,x;j<v_dcc[i].size();++j)
        {
            x=v_dcc[i][j];
            if(cur[x]) {add(pos[x],i); add(i,pos[x]);}
            else pos[x]=i;
        }
    }
    cnt=num;
    return;
}
//************************************************************
void e_dcc_tarjan(int x,int fa)  //无向图->边双联通分量(找桥、割边)
{
    low[x]=dfn[x]=++indx;
    for(Reg int i=fir[x];i;i=lian[i].next)
    {
        if(lian[i].ed==fa) continue;
        if(!dfn[lian[i].ed])
        {
            e_dcc_tarjan(lian[i].ed,x);
            low[x]=min(low[x],low[lian[i].ed]);
            if(low[lian[i].ed]>dfn[x])
                lian[i].cur=lian[i^1].cur=1;  //要改两条边，具体情况具体修改
        }
        else low[x]=min(low[x],dfn[lian[i].ed]);
    }
    return;
}
//************************************************************
void e_dcc_tarjan(int x,int fa)  //无向图->边双联通分量(找边双联通)
{
    low[x]=dfn[x]=++indx;
    stack[++stack[0]]=x;
    for(Reg int i=fir[x];i;i=lian[i].next)
    {
        if(lian[i].ed==fa) continue;
        if(!dfn[lian[i].ed])
        {
            e_dcc_tarjan(lian[i].ed,x);
            low[x]=min(low[x],low[lian[i].ed]);
        }
        else low[x]=min(low[x],dfn[lian[i].ed]);
    }
    if(low[x]==dfn[x])
    {
        ++cnt;
        while(stack[stack[0]]!=x)
        {
            pos[stack[stack[0]]]=cnt;
            e_dcc[cnt].push_back(stack[stack[0]--]);
        }
        pos[stack[stack[0]]]=cnt;
        e_dcc[cnt].push_back(stack[stack[0]--]);
    }
    return;
}
void e_dcc_union()  //无向图->边双联通分量(缩点)
{
    for(Reg int i=1;i<=tot;++i)
        if(pos[lian[i].st]!=pos[lian[i].ed])
            add(pos[lian[i].st],pos[lian[i].ed]);
    return;
}
//************************************************************
void scc_tarjan(int x)  //有向图->强联通分量(找强联通)
{
    low[x]=dfn[x]=++indx;
    stack[++stack[0]]=x; ins[x]=1;
    for(Reg int i=fir[x];i;i=lian[i].next)
    {
        if(!dfn[lian[i].ed])
        {
            scc_tarjan(lian[i].ed);
            low[x]=min(low[x],low[lian[i].ed]);
        }
        else if(ins[lian[i].ed])
            low[x]=min(low[x],dfn[lian[i].ed]);
    }
    if(low[x]==dfn[x])
    {
        ++cnt;
        while(stack[stack[0]]!=x)
        {
            pos[stack[stack[0]]]=cnt;
            scc[cnt].push_back(stack[stack[0]--]);
        }
        pos[stack[stack[0]]]=cnt;
        scc[cnt].push_back(stack[stack[0]--]);
    }
    return;
}
void scc_union()  //有向图->强联通分量(缩点)
{
    for(Reg int i=1;i<=tot;++i)
        if(pos[lian[i].st]!=pos[lian[i].ed])
            add(pos[lian[i].st],pos[lian[i].ed]);
    return;
}
//************************************************************