Submission #99851

#	Time	Username	Problem	Language	Result	Execution time	Memory
99851		TadijaSebez	Duathlon (APIO18_duathlon)	C++11	23 / 100	232 ms	36744 KiB

count_triplets

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
const int N=200050;
vector<int> G[N],E[N];
void AddEdge(int u, int v){ E[u].pb(v);E[v].pb(u);}
int cnt,disc[N],low[N],tid,n,csz[N];
bool in[N];
stack<int> s;
void Tarjan(int u)
{
	disc[u]=low[u]=++tid;
	in[u]=1;s.push(u);
	for(int v:G[u])
	{
		if(!disc[v])
		{
			Tarjan(v);
			low[u]=min(low[u],low[v]);
			if(low[v]>=disc[u])
			{
				++cnt;
				AddEdge(u,cnt);
				csz[cnt]++;
				int h;
				do
				{
					h=s.top();
					s.pop();
					in[h]=0;
					AddEdge(h,cnt);
					csz[cnt]++;
				}while(h!=v);
			}
		}
		else if(in[v]) low[u]=min(low[u],disc[v]);
	}
}
ll ans;
int sz[N],dep[N],up[N];
void DFSSZ(int u, int p)
{
	sz[u]=u<=n;
	dep[u]=dep[p]+(u<=n);
	up[u]=n;
	for(int v:E[u]) if(v!=p) DFSSZ(v,u),sz[u]+=sz[v],up[u]-=sz[v];
}
int rt[N],par[N];
ll all[N],up_all[N],down_all[N];
void Solve(int u, int p, int root)
{
	par[u]=p;
	all[u]=(ll)(sz[root]-(u<=n))*(sz[root]-(u<=n)-1);
	all[u]-=(ll)(sz[root]-sz[u])*(sz[root]-sz[u]-1);
	for(int v:E[u]) if(v!=p) all[u]-=(ll)sz[v]*(sz[v]-1);
	down_all[u]=(ll)(sz[u]-(u<=n))*(sz[u]-(u<=n)-1);
	for(int v:E[u]) if(v!=p) down_all[u]-=(ll)sz[v]*(sz[v]-1);
	if(p)
	{
		up_all[u]=all[p];
		up_all[u]-=(ll)(sz[root]-(p<=n))*(sz[root]-(p<=n)-1);
		up_all[u]+=(ll)(sz[root]-sz[u]-(p<=n))*(sz[root]-sz[u]-(p<=n)-1);
		up_all[u]+=(ll)sz[u]*(sz[u]-1);
	}
	for(int v:E[u]) if(v!=p) Solve(v,u,root);
	if(u<=n)
	{
		ans+=all[u];
		for(int v:E[u]) if(v!=p) ans+=down_all[v];
		//if(p) ans+=up_all[u];
	}
	//printf("u:%i ans:%lld all:%lld up_all:%lld down_all:%lld\n",u,ans,all[u],up_all[u],down_all[u]);
	/*ll all=(ll)sz[u]*(sz[u]-1);
	int ch=0;
	for(int v:E[u]) if(v!=p) all-=(ll)sz[v]*(sz[v]-1),ch+=csz[v]-1;
	if(u<=n) ans+=(ll)(sz[root]-1)*dep[p]*2;
	ans-=all*(dep[u]+dep[p]);
	//else ans-=all*(dep[u]+dep[p]);
	//printf("all:%lld\n",all);
	/*if(u<=n)
	{
		if(p) ans-=(ll)sz[u]*(csz[p]-1)*2*2;
		ans-=(ll)up[u]*ch*2*2;
		//printf("u:%i ans:%lld sz:%i up:%i dep:%i ch:%i csz[p]:%i\n",u,ans,sz[u],up[u],dep[u],ch,csz[p]);
	}*//*
	if(u>n)
	{
		//ans-=(ll)sz[root]*(csz[u]-1)*4;
		ans+=(ll)(sz[root]-csz[u])*(csz[u]-1)*(csz[u]-2)*2;
		ans+=(ll)csz[u]*(csz[u]-1)*(csz[u]-2);
		for(int v:E[u]) if(v!=p)
		{
			//ans-=(ll)(sz[u]-sz[v]);
			ans+=(ll)(sz[root]-sz[v]-csz[u]+1)*(sz[v]-1)*(csz[u]-2);
		}
		ans+=(ll)(sz[root]-up[p]-csz[u]+1)*(up[p]-1)*(csz[u]-2);
	}
	rt[u]=root;
	//else printf("u:%i ans:%i\n",u,ans);*/
}
int main()
{
	int m,u,v;
	scanf("%i %i",&n,&m);
	cnt=n;
	for(int i=1;i<=m;i++) scanf("%i %i",&u,&v),G[u].pb(v),G[v].pb(u);
	vector<int> root;
	for(int i=1;i<=n;i++) if(!disc[i]) Tarjan(i),root.pb(i);
	for(int i:root) DFSSZ(i,0),Solve(i,0,i);
	//for(int i=n+1;i<=cnt;i++) ans+=(ll)csz[i]*(csz[i]-1)*sz[rt[i]]*2-(ll)csz[i]*(csz[i]-1)*(csz[i]-2);
	printf("%lld\n",ans);
	return 0;
}

Compilation message (stderr)

count_triplets.cpp:81:2: warning: "/*" within comment [-Wcomment]
  /*if(u<=n)
   
count_triplets.cpp: In function 'int main()':
count_triplets.cpp:105:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%i %i",&n,&m);
  ~~~~~^~~~~~~~~~~~~~~
count_triplets.cpp:107:55: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(int i=1;i<=m;i++) scanf("%i %i",&u,&v),G[u].pb(v),G[v].pb(u);
                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~

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