71 lines
1.6 KiB
C++
71 lines
1.6 KiB
C++
#include<iostream>
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#include<cstdio>
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#include<cstring>
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#include<algorithm>
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#include<stack>
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using namespace std;
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#define MAXN 5555
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struct Edge{
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int v,next;
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}edge[MAXN*MAXN];
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int n,m,NE;
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int head[MAXN];
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void Insert(int u,int v)
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{
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edge[NE].v=v;
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edge[NE].next=head[u];
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head[u]=NE++;
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}
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int cnt,rt_son,block;
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int low[MAXN],dfn[MAXN];
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int blocks[MAXN];
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bool mark[MAXN];
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void Tarjan(int u,int vv)
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{
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low[u]=dfn[u]=++cnt;
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mark[u]=true;
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for(int i=head[u];i!=-1;i=edge[i].next){
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int v=edge[i].v;
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if(v==vv)continue;
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if(dfn[v]==0){
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Tarjan(v,vv);
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low[u]=min(low[u],low[v]);
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if(low[v]>=dfn[u]){
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blocks[u]++;
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}
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}else if(mark[v]){
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low[u]=min(low[u],dfn[v]);
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}
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}
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}
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int main()
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{
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int u,v,ans;
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while(~scanf("%d%d",&n,&m)){
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NE=0;
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memset(head,-1,sizeof(head));
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while(m--){
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scanf("%d%d",&u,&v);
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Insert(u,v);
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Insert(v,u);
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}
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ans=0;
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for(int u=0;u<n;u++){
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memset(mark,false,sizeof(mark));
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memset(dfn,0,sizeof(dfn));
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fill(blocks,blocks+n,1);
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cnt=block=0;
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for(int v=0;v<n;v++)if(u!=v&&!mark[v]){
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block++;
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blocks[v]=0;
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Tarjan(v,u);
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}
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for(int v=0;v<n;v++)if(v!=u){
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ans=max(ans,block+blocks[v]-1);
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}
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}
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printf("%d\n",ans);
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}
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return 0;
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}
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