UOJ79模板
#include<cstdio>
#include<cctype>
#include<cstring>
#include<algorithm>
using namespace std;
int read() {
int x=0,f=1;
char c=getchar();
for (;!isdigit(c);c=getchar()) if (c=='-') f=-1;
for (;isdigit(c);c=getchar()) x=x*10+c-'0';
return x*f;
}
const int maxn=505;
const int maxm=maxn*maxn*2;
int n,m,que[maxm],ql,qr,pre[maxn],tim=0;
struct edge {
int v,nxt;
} e[maxm];
int h[maxn],tot=0;
int match[maxn],f[maxn],tp[maxn],tic[maxn];
int find(int x) {
return f[x]==x?f[x]:f[x]=find(f[x]);
}
void add(int u,int v) {
e[++tot]=(edge){v,h[u]};
h[u]=tot;
}
int lca(int x,int y) {
for (++tim;;swap(x,y)) if (x) {
x=find(x);
if (tic[x]==tim) return x; else tic[x]=tim,x=pre[match[x]];
}
}
void shrink(int x,int y,int p) {
while (find(x)!=p) {
pre[x]=y,y=match[x];
if (tp[y]==2) tp[y]=1,que[++qr]=y;
if (find(x)==x) f[x]=p;
if (find(y)==y) f[y]=p;
x=pre[y];
}
}
bool aug(int s) {
for (int i=1;i<=n;++i) f[i]=i;
memset(tp,0,sizeof tp),memset(pre,0,sizeof pre);
tp[que[ql=qr=1]=s]=1; // 1: type A ; 2: type B
int t=0;
while (ql<=qr) {
int x=que[ql++];
for (int i=h[x],v=e[i].v;i;i=e[i].nxt,v=e[i].v) {
if (find(v)==find(x) || tp[v]==2) continue;
if (!tp[v]) {
tp[v]=2,pre[v]=x;
if (!match[v]) {
for (int now=v,last,tmp;now;now=last) {
last=match[tmp=pre[now]];
match[now]=tmp,match[tmp]=now;
}
return true;
}
tp[match[v]]=1,que[++qr]=match[v];
} else if (tp[v]==1) {
int l=lca(x,v);
shrink(x,v,l);
shrink(v,x,l);
}
}
}
return false;
}
int main() {
n=read(),m=read();
for (int i=1;i<=m;++i) {
int x=read(),y=read();
add(x,y),add(y,x);
}
int ans=0;
for (int i=1;i<=n;++i) ans+=(!match[i] && aug(i));
printf("%d\n",ans);
for (int i=1;i<=n;++i) printf("%d ",match[i]);
puts("");
return 0;
}