Submission #671861

#	Time	Username	Problem	Language	Result	Execution time	Memory
671861		tengiz05	Port Facility (JOI17_port_facility)	C++17	22 / 100	4716 ms	1048576 KiB

port_facility

#include <bits/stdc++.h>

using i64 = long long;

constexpr int P = 1E9 + 7;

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;
    }
    
    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);
    std::vector<std::vector<int>> adj(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);
                        }
                        adj[id[u]].push_back(id[k]);
                        adj[id[k]].push_back(id[u]);
                        dfs(k);
                        l = k + 1;
                    } else {
                        break;
                    }
                }
            };
            dfs(i);
        }
    }
    
    std::vector<int> color(n);
    vis.assign(n, false);
    int c = 0;
    for (int i = 0; i < n; i++) {
        if (!vis[i]) {
            c++;
            std::function<void(int)> dfs = [&](int u) {
                vis[u] = true;
                for (int v : adj[u]) {
                    if (!vis[v]) {
                        color[v] = color[u] ^ 1;
                        dfs(v);
                    }
                }
            };
            dfs(i);
        }
    }
    
    std::stack<int> st[2];
    for (int i = 0; i < m; i++) {
        if (p[i] > i) {
            st[color[id[i]]].push(id[i]);
        } else {
            if (st[color[id[i]]].top() != id[i]) {
                std::cout << "0\n";
                return 0;
            }
            st[color[id[i]]].pop();
        }
    }
    
    int ans = 1;
    for (int i = 0; i < c; i++) {
        ans = 2 * ans % P;
    }
    
    std::cout << ans << "\n";
    
    return 0;
}

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