题解，求关注

#include<bits/stdc++.h>
#define ll long long
using namespace std;
bool a[55][55],v[55];
int n,m,uu,vv;
int ans=0,p[55];
int main(){
    scanf("%d",&n);
    for(int i=1;i<=n;i++) p[i]=i;
    while(scanf("%d%d",&uu,&vv)==2) a[uu][vv]=a[vv][uu]=1;
     
    int T=50000000/n/n;
    while(T--){
        random_shuffle(p+1,p+n+1);
         
        int now=0;
        memset(v,0,sizeof(v));
         
        for(int i=1;i<=n;i++){
            if(v[p[i]]) continue;
            v[p[i]]=1;
            now++;
             
            for(int j=1;j<=n;j++) if(!a[p[i]][j]) v[j]=1;
        }
         
        ans=max(ans,now);
    }
     
    printf("%d\n",ans);
     
    return 0;
}