poj 1144 Network 无向图求割点

#include<iostream>
#include<cstdio>
#include<cmath>
#include<string>
#include<queue>
#include<algorithm>
#include<stack>
#include<cstring>
#include<vector>
#include<list>
#include<set>
#include<map>
using namespace std;
#define ll long long
#define mod 1000000007
#define inf 999999999
int scan()
{
    int res = 0 , ch ;
    while( !( ( ch = getchar() ) >= ‘0‘ && ch <= ‘9‘ ) )
    {
        if( ch == EOF )  return 1 << 30 ;
    }
    res = ch - ‘0‘ ;
    while( ( ch = getchar() ) >= ‘0‘ && ch <= ‘9‘ )
        res = res * 10 + ( ch - ‘0‘ ) ;
    return res ;
}
int dfn[1010];
int low[1010];
int head[1010];
int ans[1010];
int visit[1010];
int index,root,son,node,jiedge;
struct is
{
    int u,v;
    int next;
}edge[1010];
void add(int x,int y)
{
    jiedge++;
    edge[jiedge].u=x;
    edge[jiedge].v=y;
    edge[jiedge].next=head[x];
    head[x]=jiedge;
    jiedge++;
    edge[jiedge].u=y;
    edge[jiedge].v=x;
    edge[jiedge].next=head[y];
    head[y]=jiedge;
}
void dfs(int u)
{
    for(int i=head[u];i;i=edge[i].next)
    {
        int v=edge[i].v;
        if(visit[v]==0)
        {
            visit[v]=1;++index;
            dfn[v]=low[v]=index;
            dfs(v);
            low[u]=min(low[u],low[v]);
            if(low[v]>=dfn[u])
            {
                if(u==root)
                son++;
                else
                ans[u]++;
            }
        }
        else
        low[u]=min(low[u],dfn[v]);
    }
}
void trajan()
{
    memset(visit,0,sizeof(visit));
    memset(ans,0,sizeof(ans));
    index=1;
    root=1;
    son=0;
    low[1]=dfn[1]=1;
    visit[1]=1;
    dfs(1);
}
int main()
{
    int u,v;
    int flag=0;
    while(scanf("%d",&node)!=EOF)
    {
        memset(head,0,sizeof(head));
        jiedge=0;
        if(node==0)break;
        while(1)
        {
            int u,v;
            scanf("%d",&u);
            if(!u)break;
            while(getchar()!=‘\n‘)
            {
                scanf("%d",&v);
                add(u,v);
            }
        }
        trajan();
        int answer=0;
        if(son>1)
        answer++;
        for(int i=2;i<=node;i++)
        if(ans[i])
        answer++;
        printf("%d\n",answer);
    }
    return 0;
}