uva 315 Network 割点

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//uva 315//割点条件根节点有两个或两个以上节点//或者其他节点u有一个子女w，low[w]>=dfn[u];#include<bits/stdc++.h>using namespace std;const int MAXN=1000+5;struct Edge{    int from,to;};vector<Edge>edges;vector<int>G[MAXN*MAXN];int low[MAXN],dfn[MAXN],vis[MAXN],dep,ans,sub[MAXN];void addedge(int from,int to){    Edge tp;    tp.from=from;    tp.to=to;    edges.push_back(tp);    G[from].push_back(edges.size()-1);}void dfs(int u){    for(int i=0; i<G[u].size(); i++)    {        int v=edges[G[u][i]].to;        if(!vis[v])        {            vis[v]=1;            dep++;            dfn[v]=low[v]=dep;            dfs(v);            low[u]=min(low[u],low[v]);            if(low[v]>=dfn[u])            {                sub[u]++;            }        }        else            low[u]=min(low[u],dfn[v]);    }}int main(){    int _,i,j,u,v,c,n;    char st;    while(~scanf("%d",&n))    {        if(n==0) break;        ans=0;        edges.clear();        for(i=0; i<MAXN; i++)            G[i].clear();        while(~scanf("%d",&u))        {            if(u==0) break;            while(1)            {                st=getchar();                if(st==10) break;                scanf("%d",&v);                addedge(u,v);                addedge(v,u);            }        }        memset(vis,0,sizeof(vis));        memset(sub,0,sizeof(sub));        dep=0;        for(i=1; i<=n; i++)        {            if(vis[i]==0)            {                vis[i]=1;                dep++;                dfn[i]=low[i]=dep;                dfs(i);                if(sub[i]>=1)sub[i]-=1;            }        }        for(i=1; i<=n; i++)        {            if(sub[i])                ans++;        }        printf("%d\n",ans);    }    return 0;}
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