Submission #1243194

#	Time	Username	Problem	Language	Result	Execution time	Memory
1243194		lioow	Shymbulak (IZhO14_shymbulak)	C++20	0 / 100	39 ms	13632 KiB

shymbulak

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#define pb push_back
#define int long long
#define repp(i,x,n) for(int i=x;i<=n;i++)
#define rep(i,x,n) for(int i=x;i>=n;i--)
#define r0 return 0
#define fi first
#define se second
#define liow ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
#define jelek cout<<"jelek"<<endl
#define pii pair<int,int>
#define all(v) v.begin(),v.end()
#define tp tuple<int,int,int>
#define fl fflush(stdout)
#define ld long double
#define p5 pair<int,pair<pair<int,int>,pair<int,int>>>
#pragma GCC optimize ("O2")
#pragma GCC optimize ("unroll-loops")  
using namespace std;
using namespace __gnu_pbds;
typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
typedef tree<pair<int,int>, null_type,  less<pair<int,int>>, rb_tree_tag, tree_order_statistics_node_update> ordered_multiset;
//const int mod=1e9+7;
const int SQMAX=635,INF=1e18;
const int mod=998244353;
//const int MOD=1e6+3;
mt19937_64 rng((unsigned int) chrono::steady_clock::now().time_since_epoch().count());
pii dr[8]={{-1,0},{-1,1},{0,1},{1,1},{1,0},{1,-1},{0,-1},{-1,-1}};
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
int dxx[4]={1,1,-1,-1};
int dyy[4]={1,-1,-1,1};
int mul(int x,int y){return (x%mod*y%mod)%mod;}
int expo(int b,int e){
	if(e==0) return 1;
	int tmp=expo(b,e/2);
	if(e%2) return mul(tmp,mul(tmp,b));
	else return mul(tmp,tmp);
}
const int maxn=2e5;
vector<int>adj[maxn+2];
int maks=0;
int sz[maxn+2];
int sais=0;
vector<bool>cyc(maxn+2,1),visi(maxn+2,0);
vector<int>vv;
void dfs(int x,int p,int dis){
	if(dis>maks){
		maks=dis;
		sais=1;
	} else if(dis==maks){
		sais++;
	}
	for(auto v:adj[x]){
		if(!cyc[v] && v!=p) dfs(v,x,dis+1);
	}
}
void dfs2(int x,int p){
	vv.pb(x);
	visi[x]=1;
	for(auto v:adj[x]){
		if(v==p) continue;
		if(cyc[v] && !visi[v]) dfs2(v,x);
	}
}
//11
//1 2
//2 3
//3 4
//4 1
//4 11
//3 7
//3 8
//2 10
//2 9
//1 5
//1 6
void solve(){
	int n;cin>>n;
	vector<int>deg(n+2);
	repp(i,1,n){
		int u,v;cin>>u>>v;
		adj[u].pb(v);
		adj[v].pb(u);
		deg[u]++,deg[v]++;
	}
	queue<int>q;
	repp(i,1,n) if(deg[i]==1) q.push(i),cyc[i]=0;
	while(!q.empty()){
		int x=q.front();q.pop();
		for(auto v:adj[x]){
			if(cyc[v] && deg[v]==1){
				q.push(v);
				cyc[v]=0;
			}
			deg[v]--;
		}
	}
	vector<int>sz(n+2),jauh(n+2);
	repp(i,1,n){
		if(cyc[i]){
//			cout<<"cyc "<<i<<" ";
			maks=0;
			sais=0;
			dfs(i,0,0);
//			cout<<maks<<" "<<sais<<endl;
			sz[i]=sais;
			jauh[i]=maks;
		}
	}
//	jelek;
	int stt;
	repp(i,1,n){
		if(cyc[i]){
			stt=i;
			break;
		}
	}
	dfs2(stt,0);
//	jelek;
	// v idx cycle nya
//	for(auto x:vv) cout<<x<<" ";
//	cout<<endl;
	int ans=0,mx=0;
	deque<pii>dq;
	int i=0;
	multiset<pii>st;
	n=vv.size();
	repp(i,0,n/2) dq.push_front({jauh[vv[i]]+i,i}),st.insert({jauh[vv[i]]+i,i});
//	repp(i,0,n-1) cout<<jauh[vv[i]]<<endl;
	int brp=0;
	while(1){
//		for(auto x:st) cout<<x.fi<<" "<<x.se<<endl;
		int mak=st.rbegin()->fi+brp;
		if(mx<jauh[vv[i]]+mak){
			mx=jauh[vv[i]]+mak;
			if((i+n/2)%n==st.rbegin()->se) ans=2*sz[vv[i]]*sz[vv[st.rbegin()->se]];
			else ans=sz[vv[i]]*sz[vv[st.rbegin()->se]];
		} else if(mx==jauh[vv[i]]+mak){
			if((i+n/2)%n==st.rbegin()->se) ans+=2*sz[vv[i]]*sz[vv[st.rbegin()->se]];
			else ans+=sz[vv[i]]*sz[vv[st.rbegin()->se]];
		}
//		cout<<"i "<<i<<" ans "<<ans<<" mak "<<mak<<" mx "<<mx<<" .se "<<st.rbegin()->se<<endl;
		pii out=dq.back();
		dq.pop_back();
		if(st.find(out)!=st.end()) st.erase(st.find(out));
		brp++;
		i=((i-1)+n)%n;
		jauh[vv[i]]-=brp;
		dq.push_front({jauh[vv[i]],i});
		st.insert({jauh[vv[i]],i});
		if(i==0) break;
	}
	cout<<ans<<endl;
}

signed main(){
  liow;
  int t=1;
 //cin>>t;
  while(t--){
  	solve();
  }
}

• Subtask 1: 0 / 30
• Subtask 2: 0 / 20
• Subtask 3: 0 / 50