제출 #239987

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
239987		alishahali1382	Duathlon (APIO18_duathlon)	C++14	100 / 100	249 ms	25572 KiB

count_triplets

#include <bits/stdc++.h>
#pragma GCC optimize ("O2,unroll-loops")
//#pragma GCC optimize("no-stack-protector,fast-math")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<pii, int> piii;
typedef pair<ll, ll> pll;
#define debug(x) cerr<<#x<<'='<<(x)<<endl;
#define debugp(x) cerr<<#x<<"= {"<<(x.first)<<", "<<(x.second)<<"}"<<endl;
#define debug2(x, y) cerr<<"{"<<#x<<", "<<#y<<"} = {"<<(x)<<", "<<(y)<<"}"<<endl;
#define debugv(v) {cerr<<#v<<" : ";for (auto x:v) cerr<<x<<' ';cerr<<endl;}
#define all(x) x.begin(), x.end()
#define pb push_back
#define kill(x) return cout<<x<<'\n', 0;

const ld eps=1e-7;
const int inf=1000000010;
const ll INF=10000000000000010LL;
const int mod=1000000007;
const int MAXN=200010, LOG=20;

int n, m, k, u, v, x, y, t, a, b;
ll sz[MAXN], dp[MAXN], ans;
int par[MAXN], h[MAXN];
bool good[MAXN];
vector<int> G[MAXN], bcc;
vector<pii> E;

int dfs1(int node){
	int res=h[node]=h[par[node]]+1;
	bcc.pb(node);
	for (int v:G[node]){
		if (!h[v]) par[v]=node, res=min(res, dfs1(v));
		else res=min(res, h[v]);
	}
	if (res==h[par[node]]){
		while (1){
			int v=bcc.back();
			bcc.pop_back();
			E.pb({node+n, v});
			if (v==node) break ;
		}
		E.pb({node+n, par[node]});
	}
	if (!par[node]) bcc.pop_back();
	return res;
}

void dfs2(int node){
	sz[node]=(node<=n);
	for (int v:G[node]) if (v!=par[node]){
		par[v]=node;
		dfs2(v);
		sz[node]+=sz[v];
	}
}

void dfs3(int node, ll ted){
	dp[node]=(ted-2*(node<=n))*(ted-1)-(ted-sz[node])*(ted-sz[node]-1);
	for (int v:G[node]) if (v!=par[node]) dp[node]-=sz[v]*(sz[v]-1);
	for (int v:G[node]) if (v!=par[node]) dfs3(v, ted);
}

void dfs4(int node, ll ted){
	if (node<=n){
		ans+=dp[node];
//		ll shit=ans;
		for (int v:G[node]) if (v!=par[node]) ans+=dp[v]-2*sz[v]*(ted-sz[v]);
		if (par[node]){
			ans+=dp[par[node]];
			ans-=2*sz[node]*(ted-sz[node]);
		}
//		debug2(node, ans-shit)
	
	}
	for (int v:G[node]) if (v!=par[node]) dfs4(v, ted);
}

int main(){
	ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
	//freopen("input.txt", "r", stdin);
	//freopen("output.txt", "w", stdout);
	cin>>n>>m;
	while (m--){
		cin>>u>>v;
		G[u].pb(v);
		G[v].pb(u);
	}
	for (int i=1; i<=n; i++){
		if (!h[i]) dfs1(i);
		G[i].clear();
		par[i]=0;
	}
	for (pii p:E){
//		debugp(p)
		G[p.first].pb(p.second);
		G[p.second].pb(p.first);
	}
	for (int i=1; i<=n; i++) if (!par[i]){
		dfs2(i);
		dfs3(i, sz[i]);
		dfs4(i, sz[i]);
	}
	cout<<ans<<'\n';
//	debug(dp[1])
	
//	debug(dp[7])
	
	return 0;
}
/*
4 3
1 2
2 3
3 4

4 4
1 2
2 3
3 4
4 2

*/

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