Submission #671828

#	Time	Username	Problem	Language	Result	Execution time	Memory
671828		tengiz05	Port Facility (JOI17_port_facility)	C++17	0 / 100	0 ms	212 KiB

port_facility

#include <bits/stdc++.h>

using i64 = long long;

constexpr int P = 1E9 + 7;

struct DSU {
    std::vector<int> f, siz;
    DSU(int n) : f(n), siz(n, 1) { std::iota(f.begin(), f.end(), 0); }
    int leader(int x) {
        while (x != f[x]) x = f[x] = f[f[x]];
        return x;
    }
    bool same(int x, int y) { return leader(x) == leader(y); }
    bool merge(int x, int y) {
        x = leader(x);
        y = leader(y);
        if (x == y) return false;
        siz[x] += siz[y];
        f[y] = x;
        return true;
    }
    int size(int x) { return siz[leader(x)]; }
    int count() {
        int cnt = 0;
        for (int i = 0; i < int(f.size()); i++) {
            cnt += f[i] == i;
        }
        return cnt;
    }
};

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(NULL);
    
    int n;
    std::cin >> n;
    
    std::vector<std::pair<int, int>> a(n);
    std::vector<int> p(2 * n), id(2 * n);
    for (int i = 0; i < n; i++) {
        std::cin >> a[i].first >> a[i].second;
        a[i].first--;
        a[i].second--;
        p[a[i].first] = a[i].second;
        p[a[i].second] = a[i].first;
        id[a[i].first] = id[a[i].second] = i;
    }
    
    DSU d(n);
    
    int m = 2 * n;
    
    std::vector mx(21, std::vector<int>(m));
    
    for (int i = 0; i < m; i++) {
        mx[0][i] = p[i];
    }
    for (int j = 0; (1 << (j + 1)) <= m; j++) {
        for (int i = 0; i + (1 << (j + 1)) <= m; i++) {
            if (mx[j][i] > mx[j][i + (1 << j)]) {
                mx[j + 1][i] = mx[j][i];
            } else {
                mx[j + 1][i] = mx[j][i + (1 << j)];
            }
        }
    }
    
    auto query = [&](int l, int r) {
        int k = std::__lg(r - l);
        if (mx[k][l] > mx[k][r - (1 << k)]) {
            return mx[k][l];
        } else {
            return mx[k][r - (1 << k)];
        }
    };
    
    std::vector<bool> vis(n);
    for (int i = 0; i < m; i++) {
        if (!vis[id[i]]) {
            std::function<void(int)> dfs = [&](int u) {
                vis[id[u]] = true;
                int l = u + 1;
                int r = p[u];
                while (l < r) {
                    int k = query(l, r);
                    k = p[k];
                    if (p[k] > r) {
                        if (l < k && query(l, k) > r) {
                            std::cout << "0\n";
                            std::exit(0);
                        }
                        if (!d.merge(id[u], id[k])) {
                            std::cout << "0\n";
                            std::exit(0);
                        }
                        dfs(k);
                        l = k + 1;
                    } else {
                        break;
                    }
                }
            };
            dfs(i);
        }
    }
    
    int ans = 1;
    int c = d.count();
    for (int i = 0; i < c; i++) {
        ans = 2 * ans % P;
    }
    
    std::cout << ans << "\n";
    
    return 0;
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 12
• Subtask 3: 0 / 56
• Subtask 4: 0 / 22