Submission #287325

#	Time	Username	Problem	Language	Result	Execution time	Memory
287325		wiwiho	Duathlon (APIO18_duathlon)	C++14	0 / 100	1087 ms	36752 KiB

count_triplets

//#define NDEBUG

#include <bits/stdc++.h>
#include <bits/extc++.h>

#define StarBurstStream ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define iter(a) a.begin(), a.end()
#define riter(a) a.rbegin(), a.rend()
#define lsort(a) sort(iter(a))
#define gsort(a) sort(riter(a))
#define pb(a) push_back(a)
#define eb(a) emplace_back(a)
#define pf(a) push_front(a)
#define pob pop_back()
#define pof pop_front()
#define mp(a, b) make_pair(a, b)
#define F first
#define S second
#define mt make_tuple
#define gt(t, i) get<i>(t)
#define iceil(a, b) (((a) + (b) - 1) / (b))
#define tomax(a, b) ((a) = max((a), (b)))
#define printv(a, b) {bool pvaspace=false; \
for(auto pva : a){ \
    if(pvaspace) b << " "; pvaspace=true;\
    b << pva;\
}\
b << "\n";}

//#define TEST

using namespace std;
using namespace __gnu_pbds;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;

using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<ld, ld>;
using tiii = tuple<int, int, int>;

const ll MOD = 1000000007;
const ll MAX = 2147483647;

template<typename A, typename B>
ostream& operator<<(ostream& o, pair<A, B> p){
    return o << '(' << p.F << ',' << p.S << ')';
}

vector<vector<int>> tg, g;
int bcc;
vector<int> low, in;
int tts = 1;
stack<int> st;
vector<vector<int>> c;
vector<bool> iscut;

void dfsbcc(int now, int p){
    low[now] = in[now] = tts++;
    for(int i : tg[now]){
        if(i == p) continue;
        if(in[i]) low[now] = min(low[now], in[i]);
        else{
            dfsbcc(i, now);
            low[now] = min(low[now], low[i]);
            c[now].eb(i);
        }
        if(low[i] >= in[now] && now != 1) iscut[now] = true;
    }
    if(now == 1 && c[now].size() > 1) iscut[now] = true;
}

void dfsbcc2(int now, int p){
    st.push(now);
    for(int i : c[now]){
        dfsbcc2(i, now);
    }
    if(now == 1){
        if(st.size() > 1){
            while(!st.empty()){
                g[st.top()].eb(bcc);
                g[bcc].eb(st.top());
                st.pop();
            }
            bcc++;
        }
    }
    else if((p != 1 && low[now] >= in[p]) || (p == 1 && c[p].size() > 1)){
        while(!st.empty()){
            int t = st.top();
            g[st.top()].eb(bcc);
            g[bcc].eb(st.top());
            st.pop();
            if(t == now) break;
        }
        g[bcc].eb(p);
        g[p].eb(bcc);
        bcc++;
    }
}

vector<int> sz, cnt;

ll ans = 0;

void dfs1(int now, int p){
    sz[now] = cnt[now];
    for(int i : g[now]){
        if(i == p) continue;
        dfs1(i, now);
        sz[now] += sz[i];
    }
}

int n;

void dfs2(int now, int p, int r){
    for(int i : g[now]){
        if(i == p) continue;
        ans += (ll) cnt[now] * sz[i] * (sz[r] - cnt[now] - sz[i]);
        ans += (ll) cnt[now] * (cnt[now] - 1) * sz[i] * 2;
        ans += (ll) cnt[now] * cnt[i] * (cnt[i] - 1);
//        cerr << now << " " << i << " " << r << " " << cnt[now] << " " << sz[i] << " " << sz[r] << "\n";
        cerr << now << " " << i << " " <<(ll) cnt[now] * sz[i] * (sz[r] - cnt[now] - sz[i]) << " " << (ll) cnt[now] * (cnt[now] - 1) * sz[i] * 2 << "\n";
        dfs2(i, now, r);
    }
    ans += (ll) cnt[now] * (sz[r] - sz[now]) * (sz[now] - cnt[now]);
    ans += (ll) cnt[now] * (cnt[now] - 1) * (sz[r] - sz[now]) * 2;
    ans += (ll) cnt[now] * (cnt[now] - 1) * (cnt[now] - 2);
//    cerr << "test " << now << " " <<(ll) cnt[now] * (sz[r] - sz[now]) * (sz[now] - cnt[now]) << " " << (ll) cnt[now] * (cnt[now] - 1) * (sz[r] - sz[now]) * 2 << " "
//            << (ll) cnt[now] * (cnt[now] - 1) * (cnt[now] - 2) << "\n";
}

int main(){
    StarBurstStream

    int m;
    cin >> n >> m;
    tg.resize(n + 1);
    g.resize(3 * n + 1);
    bcc = n + 1;
    low.resize(n + 1);
    in.resize(n + 1);
    c.resize(n + 1);
    iscut.resize(n + 1);

    for(int i = 0; i < m; i++){
        int u, v;
        cin >> u >> v;
        tg[u].eb(v);
        tg[v].eb(u);
    }

    for(int i = 1; i <= n; i++){
        if(in[i]) continue;
        dfsbcc(i, i);
        dfsbcc2(i, i);
    }

//    for(int i = 1; i <= n; i++){
//        cerr << i << "  ";
//        printv(g[i], cerr);
//    }

    sz.resize(3 * n + 1, -1);
    cnt.resize(3 * n + 1);
    for(int i = n + 1; i < bcc; i++){
        for(int j : g[i]){
            if(!iscut[j]) cnt[i]++;
        }
    }

    for(int i = 1; i <= n; i++) if(iscut[i]) cnt[i] = 1;

    for(int i = 1; i < bcc; i++){
        if(sz[i] != -1) continue;
        dfs1(i, i);
        dfs2(i, i, i);
    }

    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