Submission #738522

#	Time	Username	Problem	Language	Result	Execution time	Memory
738522		089487	Duathlon (APIO18_duathlon)	C++14	0 / 100	92 ms	28200 KiB

count_triplets

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx,popcnt,sse4,abm")
#include<bits/stdc++.h>
#define int long long
#define quick ios::sync_with_stdio(0);cin.tie(0);
#define rep(x,a,b) for(int x=a;x<=b;x++)
#define repd(x,a,b) for(int x=a;x>=b;x--)
#define lowbit(x) (x&-x)
#define sz(x) (int)(x.size())
#define F first
#define S second
#define all(x) x.begin(),x.end()
#define mp make_pair
#define eb emplace_back
using namespace std;
typedef pair<int,int> pii;
void debug(){
    cout<<"\n";
}
template <class T,class ... U >
void debug(T a, U ... b){
    cout<<a<<" ",debug(b...);
}
const int N=2e5+7;
const int INF=1e18;
vector<int> v[N];
vector<int> v2[N];
int in[N];
int low[N];
int t=1;
int num=0;
int group[N];
int sz[N];
bool cut[N];
stack<int> st;
void dfs(int x,int p=-1){
	in[x]=low[x]=t++;
	st.push(x);
	bool ct=false;
	for(int i:v[x]){
		if(i==p) continue;
		if(in[i]) low[x]=min(low[x],in[i]);
		else{
			dfs(i,x);
			if(in[x]<=low[i]) ct=true;
			low[x]=min(low[x],low[i]);
		}
	}
	if(p==-1){
		ct=(sz(v[x])>=2);
	}
	if(p==-1||in[p]<=low[x]){
		++num;
		while(sz(st)){
			int x2=st.top();
			st.pop();
			group[x2]=num;
			sz[num]++;
			if(x2==x) break;
		}
		cut[num]=ct;
	}
}
pii e[N];
int sum;
int Sz[N];
bool vis[N];
void dfs_sz(int x,int p=-1){
	Sz[x]=sz[x];
	for(int i:v2[x]){
		if(i!=p){
			dfs_sz(i,x);
			Sz[x]+=Sz[i];
		}
	}
	sum=Sz[x];
}
int C2(int x){
	if(x<2) return 0;
	return x*(x-1);
}
int C3(int x){
	if(x<3) return 0;
	return x*(x-1)*(x-2);
}
int ans=0;
void solve(int x,int p=-1){
	int a=Sz[x]-sz[x];
	int b=sum-Sz[x];
	int c=sz[x];
	vis[x]=true;
	ans+=a*b*c*2+C2(c)*(a+b)*2+C3(c);
	int s=0;
	for(int i:v2[x]){
		if(cut[x]){
			ans+=C2(sz[i]);
		}
		if(i!=p){
			solve(i,x);
			ans+=s*Sz[i]*c*2;
			s+=sz[i];
		}
	}
}
signed main(){
	quick
	int n,m;
	cin>>n>>m;
	rep(i,1,m){
		cin>>e[i].F>>e[i].S;
		v[e[i].F].eb(e[i].S);
		v[e[i].S].eb(e[i].F);
	}
	dfs(1);
	rep(i,1,m){
		int g1=group[e[i].F];
		int g2=group[e[i].S];
		if(g1!=g2){
			v2[g1].eb(g2);
			v2[g2].eb(g1);
		}
	}
	rep(i,1,num) sort(all(v2[i])),v2[i].erase(unique(all(v2[i])),v2[i].end());
	ans=0;
	rep(i,1,num){
		if(!Sz[i]){
			dfs_sz(i);
			solve(i);
		}
	}
	cout<<ans<<"\n";
	return 0;
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 8
• Subtask 4: 0 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 15
• Subtask 7: 0 / 20
• Subtask 8: 0 / 8
• Subtask 9: 0 / 10