#include <bits/stdc++.h>
//#pragma GCC optimize("unroll-loops")
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("-O3")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#define vec vector
#define sz(x) ( int)x.size()
#define m_p make_pair
#define f first
#define s second
#define pb push_back
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define int long long
using namespace std;
typedef long long ll;
typedef pair<ll, int> pli;
typedef pair<int,ll> pil;
typedef pair<int,int> pii;
typedef unsigned long long ull;
auto rng=bind(uniform_int_distribution<int>(1,1000),mt19937(time(0)));
template<class T> bool umax(T &a,const T &b){return (a<b?a=b,1:0);}
template<class T> bool umin(T &a,const T &b){return (a>b?a=b,1:0);}
const int N=2e5+1;
vec<int> g[N];
int n;
int dst[N];
int used[N],pr[N];
vec<int>cyc;
//vec<int>g
void dfs(int v,int p){
used[v]=1;
for(auto &z : g[v]){
if(z==p) continue;
if(used[z]==1){
int u=v;
while(u!=z){
cyc.pb(u);
u=pr[u];
}
cyc.pb(u);
}
else if(!used[z]){
pr[z]=v;
dfs(z,v);
}
}
used[v]=2;
}
pii ans=m_p(0,0);
pii dp[N];
void upd(pii &a,pii b){
if(a.f<b.f) a=b;
else if(a.f==b.f) a.s+=b.s;
}
void dfs2(int v,int p){
vec<int>vc;
dp[v]={0,1};
for(auto &z : g[v]){
if(used[z] || z==p) continue;
dfs2(z,v);
upd(dp[v],{dp[z].f+1,dp[z].s});
vc.pb(z);
}
int m=sz(vc);
vec<pii>pref(m),suf(m);
pii me={0,0};
for(int i=0;i<m;i++){
int z=vc[i];
pref[i]=me;
upd(me,{dp[z].f+1,dp[z].s});
}
for(int i=0;i<m;i++){
pii x=pref[i];
if(x.f==0) x.s=1;
upd(ans,m_p(dp[vc[i]].f+1+x.f,1ll*x.s*dp[vc[i]].s));
}
}
struct myset{
map<int,int>mp;
int ad=0;
void add(pii x){
x.f-=ad;
mp[x.f]+=x.s;
}
void del(pii x){
x.f-=ad;
assert(mp[x.f]>=x.s);
mp[x.f]-=x.s;
if(!mp[x.f]) mp.erase(x.f);
}
pii get(){
pii x={-1e9,-1};
if(sz(mp)){
x=*mp.rbegin();
}
x.f+=ad;
return x;
}
}f,s;
signed main(){
ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
cin>>n;
assert(n<=500);
for(int i=0;i<n;i++){
int v,u;
cin>>v>>u;--v;--u;
g[v].pb(u);g[u].pb(v);
}
dfs(0,0);
fill(used,used+n,0);
for(auto &z : cyc) used[z]=1;
for(auto &z : cyc){
dfs2(z,z);
}
assert(sz(cyc));
// cerr<<ans.f<<' '<<ans.s<<endl;
int l=sz(cyc)/2;
// cout<<l<<endl;
for(int i=0;i<sz(cyc);i++){
int v=cyc[i];
if(i>l){
s.add({dp[v].f+sz(cyc)-i,dp[v].s});
}
else{
f.add({dp[v].f+i,dp[v].s});
}
}
auto dst=[&](int i,int j){
int x=abs(i-j);
return min(x,sz(cyc)-x);
};
for(int i=0;i<sz(cyc);i++){
int v=cyc[i];
f.del(dp[v]);
// cerr<<<<' '<<dp[i].f<<' '<<f.get().f<<' '<<s.get().f<<endl;
pii me=f.get();
upd(ans,{me.f+dp[v].f,1ll*me.s*dp[v].s});
if(sz(cyc)%2==0){
int u=cyc[(i+l)%2];
pii x={dp[u].f+dp[v].f,1ll*dp[u].s*dp[u].s};
upd(ans,x);
}
int j=(i+l+1)%sz(cyc);
int u=cyc[j];
s.del({dp[u].f+dst(i,j),dp[u].s});
s.add(dp[v]);
s.ad++;
f.ad--;
f.add({dp[u].f+dst((i+1)%sz(cyc),j),dp[u].s});
}
// cout<<ans.f<<' '<<ans.s<<endl;
cout<<ans.s;
return 0;
}
/*
5
1 2
2 3
3 4
4 5
5 1
*/
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
3 ms |
4940 KB |
Output is correct |
| 2 |
Correct |
3 ms |
4940 KB |
Output is correct |
| 3 |
Correct |
3 ms |
4940 KB |
Output is correct |
| 4 |
Correct |
3 ms |
4940 KB |
Output is correct |
| 5 |
Correct |
3 ms |
4940 KB |
Output is correct |
| 6 |
Correct |
3 ms |
4940 KB |
Output is correct |
| 7 |
Correct |
3 ms |
4940 KB |
Output is correct |
| 8 |
Correct |
3 ms |
4940 KB |
Output is correct |
| 9 |
Correct |
3 ms |
4940 KB |
Output is correct |
| 10 |
Correct |
3 ms |
4940 KB |
Output is correct |
| 11 |
Correct |
3 ms |
4940 KB |
Output is correct |
| 12 |
Correct |
3 ms |
4940 KB |
Output is correct |
| 13 |
Correct |
3 ms |
4940 KB |
Output is correct |
| 14 |
Correct |
3 ms |
5056 KB |
Output is correct |
| 15 |
Correct |
4 ms |
5068 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
8 ms |
9932 KB |
Execution killed with signal 6 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
9 ms |
9932 KB |
Execution killed with signal 6 |
| 2 |
Halted |
0 ms |
0 KB |
- |
