Submission #1085312

#	Time	Username	Problem	Language	Result	Execution time	Memory
1085312		eysbutno	Bitaro’s Party (JOI18_bitaro)	C++17	7 / 100	2062 ms	118872 KiB

bitaro

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = array<int, 2>;
#define all(x) begin(x), end(x)
#define sz(x) (int) (x).size()

constexpr int B = 100;
int main() {
    cin.tie(0) -> sync_with_stdio(0);
    int n, m, q;
    cin >> n >> m >> q;
    vector<vector<int>> adj(n);
    vector<int> deg(n);
    for (int i = 0; i < m; i++) {
        int u, v;
        cin >> u >> v;
        --u, --v;
        adj[u].push_back(v);
        ++deg[v];
    }
    vector<vector<pii>> best(n);
    auto cur = deg;
    queue<int> top;
    for (int i = 0; i < n; i++) {
        if (!cur[i]) { top.push(i); }
    }
    const auto merge = [&](int from, int to) -> void {
        map<int, int> mp;
        for (auto [node, dist] : best[from]) {
            mp[node] = max(mp[node], dist + 1);
        }
        for (auto [node, dist] : best[to]) {
            mp[node] = max(mp[node], dist);
        }
        best[to].clear();
        for (auto [node, dist] : mp) {
            best[to].push_back({node, dist});
        }
        sort(all(best[to]), [&](auto &x, auto &y) -> bool {
            return x[1] > y[1];
        });
        if (sz(best[to]) > B) { best[to].resize(B); }
    };
    while (!top.empty()) {
        int u = top.front(); top.pop();
        if (sz(best[u]) < B) {
            best[u].push_back({u, 0});
        }
        for (int v : adj[u]) {
            merge(u, v);
            if (!(--cur[v])) { top.push(v); }
        }
    }
    const auto check = [&](int t, const set<int> &bad) -> int {
        for (auto [node, dist] : best[t]) {
            if (!bad.count(node)) {
                return dist;
            }
        }
        return -1;
    };
    const auto brute_force = [&](int t, const set<int> &bad) -> int {
        queue<int> q;
        auto cur = deg;
        vector<int> best(n, -1);
        for (int i = 0; i < n; i++) {
            if (!cur[i]) { q.push(i); }
        }
        while (!q.empty()) {
            int u = q.front(); q.pop();
            if (!bad.count(u)) { best[u] = max(0, best[u]); }
            if (u == t) { break; }
            for (int v : adj[u]) {
                if (best[u] != -1) { best[v] = max(best[v], best[u] + 1); }
                if (!--cur[v]) { q.push(v); }
            }
        }
        return best[t];
    };
    while (q--) {
        int t, y;
        cin >> t >> y;
        --t;
        set<int> bad;
        for (int i = 0; i < y; i++) {
            int x; cin >> x;
            bad.insert(--x);
        }
        if (y >= B) {
            cout << brute_force(t, bad) << "\n";
        } else {
            cout << check(t, bad) << "\n";
        }
    }
    /*
    for (int i = 0; i < n; i++) {
        cout << "node " << i + 1 << "\n";
        for (auto [node, dist] : best[i]) {
            cout << node + 1 << " " << dist << "\n";
        }
    }
    */
}

• Subtask 1: 7 / 7
• Subtask 2: 0 / 7
• Subtask 3: 0 / 86