답안 #766508

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
766508 2023-06-25T17:38:41 Z dxz05 관광지 (IZhO14_shymbulak) C++17
100 / 100
68 ms 21228 KB
#pragma GCC optimize("Ofast,O3,unroll-loops")
#pragma GCC target("avx,avx2")

#include <bits/stdc++.h>

using namespace std;

vector<vector<int>> g;

vector<int> color;
vector<int> cycle;

stack<int> st;
bool dfs0(int v, int p){
    st.push(v);
    color[v] = 1;

    for (int u : g[v]){
        if (u == p) continue;

        if (color[u] == 0){
            if (dfs0(u, v)) return true;
        }

        if (color[u] == 1){
            while (!st.empty()){
                int x = st.top();
                st.pop();
                cycle.push_back(x);
                if (x == u) break;
            }
            return true;
        }

    }

    color[v] = 2;
    st.pop();

    return false;
}

vector<bool> incycle;

#define pii pair<int, long long>
const pii inf(-1e9, 0);

pii combine(const pii &x, const pii &y){
    if (x.first > y.first) return x;
    if (x.first < y.first) return y;
    return pii(x.first, x.second + y.second);
}

pii ans = inf;

pii dfs1(int v, int p, int d){
    pii res(d, 1);

    map<int, vector<long long>> children;
    for (int u : g[v]){
        if (u == p || incycle[u]) continue;
        pii t = dfs1(u, v, d + 1);
        res = combine(res, t);
        children[t.first].push_back(t.second);
    }

    if (!children.empty()){
        int da = children.rbegin()->first;
        vector<long long> a = children.rbegin()->second;
        da -= d;

        children.erase(--children.end());

        if ((int) a.size() >= 2){
            long long sum = accumulate(a.begin(), a.end(), 0LL);
            for (long long x : a){
                sum -= x;
                ans = combine(ans, pii(2 * da, 2 * x * sum));
            }
        } else if (!children.empty()){
            int db = children.rbegin()->first;
            vector<long long> b = children.rbegin()->second;
            db -= d;

            long long sum = accumulate(b.begin(), b.end(), 0LL);
            ans = combine(ans, pii(da + db, 2 * a.front() * sum));
        }

    }

    return res;
}

struct SegmentTree{
    int n;
    vector<pii> tree;

    void build(int v, int tl, int tr, const vector<pii> &a){
        if (tl == tr){
            tree[v] = a[tl];
        } else {
            int tm = (tl + tr) >> 1;
            build(v << 1, tl, tm, a);
            build(v << 1 | 1, tm + 1, tr, a);
            tree[v] = combine(tree[v << 1], tree[v << 1 | 1]);
        }
    }

    SegmentTree(const vector<pii> &a){
        n = (int) a.size();
        tree.assign(4 * n + 5, inf);
        build(1, 0, n - 1, a);
    }

    pii get(int v, int tl, int tr, int l, int r){
        if (l <= tl && tr <= r) return tree[v];
        if (tl > r || tr < l) return inf;
        int tm = (tl + tr) >> 1;
        return combine(get(v << 1, tl, tm, l, r), get(v << 1 | 1, tm + 1, tr, l, r));
    }

    pii get(int l, int r){
        return get(1, 0, n - 1, l, r);
    }

};

int main(){
    ios_base::sync_with_stdio(false);

    int n;
    cin >> n;

    g.resize(n);
    for (int i = 0; i < n; i++){
        int u, v;
        cin >> u >> v;
        --u, --v;
        g[u].push_back(v);
        g[v].push_back(u);
    }

    color.assign(n, 0);
    dfs0(0, 0);

    int k = (int) cycle.size();

    assert(k >= 3);

    incycle.assign(n, false);
    for (int v : cycle) incycle[v] = true;

    vector<int> a(k), b(k);
    vector<pii> pos(k), neg(k);
    for (int i = 0; i < k; i++){
        int v = cycle[i];

        pii t = dfs1(v, -1, 0);
        a[i] = t.first;
        b[i] = t.second;
        pos[i] = pii(i + a[i], b[i]);
        neg[i] = pii(-i + a[i], b[i]);
    }

    SegmentTree st_pos(pos);
    SegmentTree st_neg(neg);

    int h = k / 2;
    for (int i = 0; i < k; i++){ // case one
        int tl = (i + 1) % k, tr = (i + h) % k;

        vector<pair<int, int>> seg;
        if (tl <= tr){
            seg.emplace_back(tl, tr);
        } else {
            seg.emplace_back(tl, n - 1);
            seg.emplace_back(0, tr);
        }

        for (auto [l, r] : seg){
            pii t = st_pos.get(l, r);
            if (l > i){ // i .. l .. r
                t.first += -i + a[i];
            } else { // l .. r .. i
                t.first += k - i + a[i];
            }
            t.second *= b[i];
            ans = combine(ans, t);
        }
    }

    for (int i = 0; i < k; i++){ // case two
        int tl = (i - h + k) % k, tr = (i - 1 + k) % k;

        vector<pair<int, int>> seg;
        if (tl <= tr){
            seg.emplace_back(tl, tr);
        } else {
            seg.emplace_back(tl, n - 1);
            seg.emplace_back(0, tr);
        }

        for (auto [l, r] : seg){
            pii t = st_neg.get(l, r);
            if (r < i){ // l .. r .. i
                t.first += i + a[i];
            } else { // i .. l .. r
                t.first += k + i + a[i];
            }
            t.second *= b[i];
            ans = combine(ans, t);
        }
    }

    cout << ans.second / 2 << endl;

    return 0;
}
# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 0 ms 212 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 0 ms 212 KB Output is correct
8 Correct 0 ms 212 KB Output is correct
9 Correct 0 ms 212 KB Output is correct
10 Correct 1 ms 212 KB Output is correct
11 Correct 0 ms 212 KB Output is correct
12 Correct 0 ms 212 KB Output is correct
13 Correct 0 ms 212 KB Output is correct
14 Correct 1 ms 340 KB Output is correct
15 Correct 0 ms 340 KB Output is correct
# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 468 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 1 ms 468 KB Output is correct
4 Correct 1 ms 340 KB Output is correct
5 Correct 2 ms 596 KB Output is correct
6 Correct 2 ms 724 KB Output is correct
7 Correct 2 ms 596 KB Output is correct
8 Correct 2 ms 596 KB Output is correct
9 Correct 2 ms 596 KB Output is correct
10 Correct 2 ms 596 KB Output is correct
# 결과 실행 시간 메모리 Grader output
1 Correct 31 ms 5904 KB Output is correct
2 Correct 33 ms 6476 KB Output is correct
3 Correct 64 ms 21228 KB Output is correct
4 Correct 31 ms 6324 KB Output is correct
5 Correct 29 ms 6228 KB Output is correct
6 Correct 68 ms 10828 KB Output is correct
7 Correct 47 ms 8892 KB Output is correct
8 Correct 60 ms 12236 KB Output is correct
9 Correct 62 ms 12304 KB Output is correct
10 Correct 59 ms 13896 KB Output is correct
11 Correct 57 ms 15408 KB Output is correct
12 Correct 49 ms 16044 KB Output is correct