Submission #368941

#	Time	Username	Problem	Language	Result	Execution time	Memory
368941		YJU	Duathlon (APIO18_duathlon)	C++14	0 / 100	170 ms	66144 KiB

count_triplets

#include<bits/stdc++.h>
#pragma GCC optimize("unroll-loops,no-stack-protector,Ofast")
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pll;
const ll MOD=1e9+7;
const ll MOD2=998244353;
const ll N=1e6+5;
const ld pi=acos(-1);
const ll INF=(1LL<<60);
#define SQ(i) ((i)*(i))
#define REP(i,n) for(ll i=0;i<n;i++)
#define REP1(i,n) for(ll i=1;i<=n;i++)
#define pb push_back
#define mp make_pair
#define X first
#define Y second
#define setp setprecision
#define lwb lower_bound
#define SZ(_a) (ll)_a.size()

ll n,m,x,y;
ll low[N],depth[N],cnt=0,ptr,w[N],ans,sz[N];
vector<ll> G[N],v[N];

ll stk[N],now;

void DFS1(ll nd,ll pa){
	++cnt;
	low[nd]=depth[nd]=depth[pa]+1;
	stk[++now]=nd;
	for(ll i:v[nd]){
		if(i==pa)continue;
		if(depth[i]){
			low[nd]=min(low[nd],depth[i]);
		}else{
			//
			//
			DFS1(i,nd);
			if(low[i]==depth[nd]){
				//cout<<"FIND BCC\n";
				++ptr;
				while(stk[now]!=nd){
					//cout<<stk[now]<<" ";
					++w[ptr];w[stk[now]]=-1;
					G[stk[now]].pb(ptr);
					G[ptr].pb(stk[now]);
					--now;
				}
				//cout<<stk[now]<<"\n";
				++w[ptr];w[stk[now]]=-1;
				G[stk[now]].pb(ptr);
				G[ptr].pb(stk[now]);
			}
			low[nd]=min(low[nd],low[i]);
		}
	}
}

void DFS2(ll nd,ll pa){
	sz[nd]=(nd<=n?1:0);
	for(auto i:G[nd]){
		if(i==pa)continue;
		DFS2(i,nd);
		ans+=2*w[nd]*sz[nd]*sz[i];
		sz[nd]+=sz[i];
	}
	ans+=2*w[nd]*sz[nd]*(cnt-sz[nd]);
}

int main(){
	ios_base::sync_with_stdio(0);cin.tie(0);
	cin>>n>>m;
	ptr=n;
	REP(i,m){
		cin>>x>>y;
		v[x].pb(y),v[y].pb(x);
	}
	REP1(i,n){
		if(!depth[i]){
			cnt=now=0;
			DFS1(i,0);
			DFS2(i,0);
		}
	}
	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