贴板子。求割边。将>改为>=即可判断u是否为割点。
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int INF=0x3f3f3f3f;
const int maxn=20008;
const int maxm=100008;
struct fuck{
int u,v,next;
bool ban;
}edge[maxm<<1];
int tol;
int head[maxn];
void init()
{
tol=0;
memset(head,-1,sizeof(head));
}
void addedge(int u,int v)
{
edge[tol].u=u;
edge[tol].v=v;
edge[tol].next=head[u];
edge[tol].ban=false;
head[u]=tol++;
}
int tim=0;
int pre[maxn],low[maxn];
int tarj(int u,int fa)
{
int lowu=pre[u]=++tim;
int child=0;
int i,v,lowv;
for(i=head[u];i!=-1;i=edge[i].next)
{
v=edge[i].v;
if(!pre[v])
{
child++;
lowv=tarj(v,u);
lowu=min(lowu,lowv);
if(lowv>pre[u])
{
edge[i].ban=true;
edge[i^1].ban=true;
}
}
else if(pre[v]<pre[u]&&v!=fa)
lowu=min(lowu,pre[v]);
}
low[u]=lowu;
return lowu;
}
int uni[maxn];
bool vis[maxn];
void dfs(int u,int idx)
{
int i,v;
vis[u]=true;
uni[u]=idx;
for(i=head[u];i!=-1;i=edge[i].next)
{
if(edge[i].ban||vis[edge[i].v]) continue;
v=edge[i].v;
dfs(v,idx);
}
}
int main()
{
int i,j,n,m,u,v;
while(scanf("%d%d",&n,&m)==2)
{
init();
for(i=1;i<=m;i++)
{
scanf("%d%d",&u,&v);
addedge(u,v);
addedge(v,u);
}
tim=0;
memset(pre,0,sizeof(pre));
tarj(1,-1);
memset(vis,false,sizeof(vis));
int ans=0;
for(i=1;i<=n;i++)
if(!vis[i])
{
dfs(i,i);
ans++;
}
printf("%d
",ans);
for(i=1;i<=n;i++)
{
if(i!=1) printf(" ");
printf("%d",uni[i]);
}
printf("
");
}
return 0;
}