POJ-1144 Tarjan求割点，双连通模板题

// POJ-1144 
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<cstring>
#include<string>
#include<cmath>
#include<queue>
#include<stack>
#include<map>
#include<bitset>
#include<vector>
#include<set>
using namespace std;
#pragma comment(linker, "/STACK:102400000,102400000")
#define F(i,a,b)  for (int i=a;i<b;i++)
#define FF(i,a,b) for (int i=a;i<=b;i++)
#define mes(a,b)  memset(a,b,sizeof(a))
#define INF 0x3f3f3f3f
typedef long long ll;
const int N = 110;

int n, tot, root;
int head[N], cut[N], vis[N], dfn[N], low[N];
struct Edge{int to, next; }edge[N<<1];

void Init()
{
    tot=0;
    mes(head, -1);
    mes(cut, 0);
    mes(vis, 0);
}
void Addedge(int u, int v)
{
    edge[tot].to=v;
    edge[tot].next=head[u];
    head[u]=tot++;
}
void Tarjan(int u, int fa)
{
    int son=0;
    vis[u]=1;
    dfn[u]=low[u]=++tot;
    for(int e=head[u]; e!=-1; e=edge[e].next) {
        int v=edge[e].to;
        if(vis[v]==0) {
            Tarjan(v, u);
            son++;
            low[u]=min(low[u], low[v]);
            if((u==root && son>1) || (u!=root && dfn[u]<=low[v]))   //如果u为树根且子树大于1；或者u不为树根，(u,v)为树枝边
                cut[u]=1;
        }
        else if(vis[v]==1 && v!=fa) {
            low[u]=min(low[u], dfn[v]);
        }
    }
    vis[u]=2;
}
int main()
{
    while(scanf("%d", &n) && n) {
        Init();
        int u, v;
        while(scanf("%d", &u) && u) {
            while(getchar()!=‘\n‘) {    //每一行以回车结束读入
                scanf("%d", &v);
                Addedge(u, v);
                Addedge(v, u);
            }
        }
        root=1;
        Tarjan(root, -1);
        int ans=0;
        FF(i,1,n) if(cut[i]) ans++;
        printf("%d\n", ans);
    }

    return 0;
}