题意：
给一个有n个结点的连通无向图，求它的割点个数。
思路：
裸求割点，直接上模板，这个模板是从一本书上找的，很简洁。
代码：
//poj 1144
#include <iostream>
using namespace std;
const int maxN=128;
int g[maxN][maxN];
int bridge[maxN][maxN];
int dfn[maxN],low[maxN],vis[maxN],cut[maxN];
int n; void cut_bridge(int cur,int father,int dep)
{vis[cur]=1;dfn[cur]=low[cur]=dep;int children=0;for(int i=1;i<=n;++i) if(g[cur][i]){if(i!=father&&vis[i]==1)low[cur]=min(low[cur],dfn[i]);if(vis[i]==0){cut_bridge(i,cur,dep+1);++children;low[cur]=min(low[cur],low[i]);if((father==-1&&children>1)||(father!=-1&&low[i]>=dfn[cur]))cut[cur]=1;if(low[i]>dfn[cur]){bridge[i][cur]=bridge[cur][i]=1;}}}
}int main()
{while(scanf("%d",&n)==1&&n){int x;memset(dfn,0,sizeof(dfn));memset(low,0,sizeof(low));memset(vis,0,sizeof(vis));memset(bridge,0,sizeof(bridge)); memset(cut,0,sizeof(cut));memset(g,0,sizeof(g)); while(scanf("%d",&x)==1&&x){while(getchar()!='\n'){int y;scanf("%d",&y);g[x][y]=g[y][x]=1;} }cut_bridge(1,-1,0); int ans=0;for(int i=1;i<=n;++i) if(cut[i]==1) ++ans;printf("%d\n",ans);}return 0;
}