Tarjan算法

Tarjan求强联通分量
http://www.cnblogs.com/shadowland/p/5872257.html

void tarjan(int x){
	dfn[x]=++dfs_num;
	low[x]=dfs_num;
	vis[x]=true;
	stack[++top]=x;
	for(int i=head[x];i!=0;i=e[i].next){
		int temp=e[i].to;
		if(!dfn[temp]){
			tarjan(temp);
			low[x]=min(low[x],low[temp]);
		}
		else if(vis[temp])low[x]=min(low[x],dfn[temp]);
	}
	if(dfn[x]==low[x]){
		vis[x]=false;
		color[x]=++col_num;
		while(stack[top]!=x){
			color[stack[top]]=col_num;
			vis[stack[top--]]=false;
		}
		top--;
	}
}