Submission #553441

#	Time	Username	Problem	Language	Result	Execution time	Memory
553441		urosk	Duathlon (APIO18_duathlon)	C++14	66 / 100	128 ms	30320 KiB

count_triplets

// __builtin_popcount(x)
// __builtin_popcountll(x)
#define here cerr<<"===========================================\n"
#include <bits/stdc++.h>
#define ld double
#define ll long long
#define ull unsigned long long
#define llinf 100000000000000000LL // 10^17
#define iinf 2000000000 // 2*10^9
#define pb push_back
#define popb pop_back
#define fi first
#define sc second
#define endl '\n'
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pld pair<ld,ld>
#define sz(a) int(a.size())
#define all(a) a.begin(),a.end()
#define ceri(a,l,r) {for(ll i_ = l;i_<=r;i_++) cerr<<a[i_]<< " ";cerr<<endl;}
using namespace std;

#define maxn 200005
ll n,m;
vector<ll> g[maxn];
vector<ll> v[maxn];
ll low[maxn];
ll in[maxn];
bool vis[maxn];
ll siz[maxn];
ll it = 1;
ll cnt = 1;
ll comp = 0;
stack<ll> st;
void dfs(ll u,ll par){
    comp++;
    in[u] = it++;
    low[u] = in[u];
    st.push(u);
    for(ll s : g[u]){
        if(s==par) continue;
        if(in[s]==0){
            dfs(s,u);
            if(low[s]>=in[u]){
                v[u].pb(n+cnt);
                while(sz(st)){
                    ll to = st.top();
                    st.pop();
                    v[n+cnt].pb(to);
                    if(to==s) break;
                }
                cnt++;
            }
        }
        low[u] = min(low[u],low[s]);
    }

}
ll ans = 0;
ll f3(ll x){
    return x*(x-1)*(x-2);
}
ll f2(ll x){
    return x*(x-1);
}
void dfs2(ll u){
    if(u<=n) siz[u] = 1;
    for(ll s : v[u]){
        dfs2(s);
        siz[u]+=siz[s];
        if(u>n) ans-=f2(siz[s])*sz(v[u]);
    }
    if(u>n) ans-=f2(comp-siz[u])*sz(v[u]);
}
int main(){
	ios_base::sync_with_stdio(false);cerr.tie(0);cout.tie(0);cin.tie(0);
    cin >> n >> m;
    for(ll i = 1;i<=m;i++){
        ll x,y; cin >> x >> y;
        g[x].pb(y);
        g[y].pb(x);
    }
    for(ll i = 1;i<=n;i++){
        if(in[i]==0){
            comp = 0;
            dfs(i,i);
            ans+=f3(comp);
            dfs2(i);
        }
    }
    cout<<ans<<endl;
	return 0;
}
/*
4 3
1 2
2 3
3 4
out: 8
*/
/*
4 4
1 2
2 3
3 4
4 2
out: 14
*/

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