Submission #106471

#	Time	Username	Problem	Language	Result	Execution time	Memory
106471		Frankenween	Shymbulak (IZhO14_shymbulak)	C++17	0 / 100	103 ms	11460 KiB

shymbulak

#ifdef LOCAL
#define _GLIBCXX_DEBUG
#endif
#include <bits/stdc++.h>

#define ull unsigned long long
#define pll pair<ll, ll>
#define mp make_pair
#define ll long long
#define pb push_back
#define deb(x) cout << #x << " = " << x << endl
#define all(x) x.begin(), x.end()
#define ld long double
const ll mod = (ll)1e9 + 7;
const ll BASE = 47;
const ll inf = (ll)1e18;
const long double e = 2.718281828459;
const long double pi = 3.141592653;
const ld EPS = 1e-9;


using namespace std;


template <class T>
istream& operator>>(istream &in, vector<T> &arr) {
    for (T &cnt : arr) {
        in >> cnt;
    }
    return in;
};


void solve() {
    ll n;
    cin >> n;
    vector<vector<ll>> g(n);
    for (int i = 0; i < n; i++) {
        ll a, b;
        cin >> a >> b;
        a--;
        b--;
        g[a].pb(b);
        g[b].pb(a);
    }
    vector<ll> cycle;
    vector<bool> on_cyc(n), used(n);

    function<ll(ll, ll)> dfs = [&](ll v, ll pr) {
        used[v] = true;
        for (auto u : g[v]) {
            if (u == pr) {
                continue;
            }
            if (used[u]) {
                cycle.pb(v);
                on_cyc[v] = true;
                return u;
            }
            ll res = dfs(u, v);
            if (res == -1) {
                continue;
            }
            if (res == -2) {
                return -2LL;
            }
            cycle.pb(v);
            on_cyc[v] = true;
            if (res == v) {
                res = -2;
            }
            return res;
        }
        return -1LL;
    };
    dfs(0, -1);

    vector<ll> cnt(n), diam(n + 1), h(n + 1), max_h_val(n);

    function<void(ll, ll)> dfs1 = [&](ll v, ll pr) {
        h[v] = 0;
        ll mx1 = 0, cnt1 = 0, mx2 = 0, cnt2 = 0;
        for (auto u : g[v]) {
            if (u == pr or on_cyc[u]) {
                continue;
            }
            dfs1(u, v);
            h[v] = max(h[v], h[u] + 1);
            if (mx1 < h[u] + 1) {
                mx2 = mx1;
                cnt2 = cnt1;
                cnt1 = 1;
                mx1 = h[u] + 1;
            } else if (mx1 == h[u] + 1) {
                cnt1++;
            } else if (mx2 < h[u] + 1) {
                mx2 = h[u] + 1;
                cnt2 = 1;
            } else if (mx2 == h[u] + 1) {
                cnt2++;
            }
        }
        if (cnt1 > 1) {
            diam[v] = mx1 * 2;
            cnt[v] = cnt1 * (cnt1 - 1) / 2;
        } else {
            diam[v] = mx1 + mx2;
            cnt[v] = max(cnt2, 1LL);
        }
        max_h_val[v] = max(1LL, cnt1);
    };

    for (auto v : cycle) {
        dfs1(v, -1);
    }
    map<ll, ll> pph;
    ll len = cycle.size();
    for (int i = 1; i <= len / 2; i++) {
        pph[-(h[cycle[i]] + i)] += max_h_val[cycle[i]];
    }
    vector<ll> answer(n + 1);
    for (int i = 0; i < len; i++) {
        auto value = *pph.begin();
        answer[-value.first - i + h[cycle[i]]] += value.second * max_h_val[cycle[i]];
        pph[-(h[cycle[(i + 1) % len]] + i + 1)] -= max_h_val[cycle[(i + 1) % len]];
        pph[-(h[cycle[(i + 1 + len / 2) % len]] + i + 1 + len / 2)] += max_h_val[cycle[(i + 1 + len / 2) % len]];
    }
    for (int i = 0; i < n; i++) {
        answer[diam[i]] += cnt[i];
    }
    ll i = n;
    while (answer[i] == 0) {
        i--;
    }
    cout << answer[i];
}


int main() {
#ifndef LOCAL
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
#else
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
    cout.precision(30);
    ll seed = time(0);
    cerr << "Seed: " << seed << "\n";
    srand(seed);
    solve();
    return 0;
}

• Subtask 1: 0 / 30
• Subtask 2: 0 / 20
• Subtask 3: 0 / 50