tarjan算法基础

　　

const int N=1000+5;
int head[10*N],pos;
struct Edge
{
    int to,nex;
}edge[10*N];
int dfn[N],low[N],tot,vis[N],ind,Stack[N],cnt,belong[N];
int init()
{
    CLR(head,0);
    CLR(dfn,0);
    CLR(low,0);
    CLR(vis,0);
    CLR(Stack,0);
    CLR(belong,0);
    cnt=ind=tot=pos=0;
}
void tarjan(int x)
{
    dfn[x]=low[x]=++tot;
    Stack[++ind]=x;
    vis[x]=1;
    for(int i=head[x];i;i=edge[i].nex)
    {
        int v=edge[i].to;
        if(!dfn[v])
        {
            tarjan(v);low[x]=min(low[x],low[v]);
        }
        else if(vis[v])
            low[x]=min(low[x],low[v]);
    }
    if(low[x]==dfn[x])
    {
        cnt++;
        int v;
        do
        {   
            v=Stack[ind--];
            vis[v]=0;
            belong[v]=cnt;
        }
        while(x!=v);
    }
}