제출 #1336844

#제출 시각아이디문제언어결과실행 시간메모리
1336844boclobanchat철인 이종 경기 (APIO18_duathlon)C++20
100 / 100
83 ms35516 KiB
#include<bits/stdc++.h>
using namespace std;
const int MAXN=2e5+5;
vector<int> ds[MAXN],vi[MAXN],node[MAXN];
int low[MAXN],num[MAXN],col[MAXN],tdfs=0,bcc=0,id=0;
bool joy[MAXN],ck[MAXN],kc[MAXN];
long long sz[MAXN],sub[MAXN];
stack<int> st;
long long ans=0;
void dfs(int i,int pre)
{
	int child=0;
	low[i]=num[i]=++tdfs,st.push(i);
	for(auto v:ds[i])
	{
		if(v==pre) continue;
		if(!num[v])
		{
			dfs(v,i);
			low[i]=min(low[i],low[v]),child++;
			if(low[v]>=num[i])
			{
				joy[i]=(i!=pre||child>1),node[++bcc].push_back(i);
				while(node[bcc].back()!=v) node[bcc].push_back(st.top()),st.pop();
			}
		}
		else low[i]=min(low[i],num[v]);
	}
}
void dftree(int i,int pre)
{
	sub[i]=sz[i],kc[i]=true;
	for(auto v:vi[i]) if(!kc[v])
	{
		dftree(v,i);
		sub[i]+=sub[v];
	}
}
void dftree2(int i,int pre)
{
	if(!ck[i])
	{
		long long sum=0;
		for(auto v:vi[i]) ans+=(sub[i]-sub[v]-sz[i])*sub[v]*sz[i]+sub[v]*(sub[i]-sub[v]-1)*(vi[i].size()-1);
		ans+=sz[i]*(sz[i]-1)*(sz[i]-2)+sz[i]*(sz[i]-1)*(sub[i]-sz[i])*2;
	}
	else
	{
		for(auto v:vi[i]) if(ck[v]) ans+=sub[v]*(sub[i]-sub[v]-1);
		else ans+=sz[v]*(sub[i]-sz[v]-1)+sz[v]*(sz[v]-1);
	}
	for(auto v:vi[i]) if(v!=pre)
	{
		sub[i]-=sub[v],sub[v]+=sub[i];
		dftree2(v,i);
		sub[v]-=sub[i],sub[i]+=sub[v];
	}
}
int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int n,m,cc=0;
    cin>>n>>m;
    for(int i=1;i<=m;i++)
    {
    	int l,r;
    	cin>>l>>r;
    	ds[l].push_back(r),ds[r].push_back(l);
	}
	for(int i=1;i<=n;i++) if(!num[i]) dfs(i,i);
	for(int i=1;i<=n;i++) if(joy[i]) col[i]=++id,sz[id]=1,ck[id]=true;
	for(int i=1;i<=bcc;i++)
	{
		sz[++id]=node[i].size();
		for(auto v:node[i]) if(!joy[v]) col[v]=id;
		else vi[id].push_back(col[v]),vi[col[v]].push_back(id),sz[id]--;
	}
	for(int i=1;i<=id;i++) if(!kc[i])
	{
		dftree(i,i);
		dftree2(i,i);
	}
	cout<<ans;
}
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