Submission #1222711

#	Time	Username	Problem	Language	Result	Execution time	Memory
1222711		ericl23302	Bitaro’s Party (JOI18_bitaro)	C++20	100 / 100	950 ms	410628 KiB

bitaro

#include <bits/stdc++.h>

using namespace std;

const int K = 300;

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int n, m, q; cin >> n >> m >> q;
    vector<vector<int>> adjacency(n);
    vector<vector<pair<int, int>>> preComp(n);
    for (int i = 0; i < m; ++i) {
        int a, b; cin >> a >> b; --a; --b;
        adjacency[b].push_back(a);
    }
    
    vector<bool> included(n, false);
    vector<int> modified;
    for (int i = 0; i < n; ++i) {
        if (adjacency[i].empty()) {
            preComp[i].push_back({0, i});
            continue;
        }
        vector<int> cnts(adjacency[i].size(), 0);
        while (preComp[i].size() <= K) {
            int cur = -1;
            for (int j = 0; j < adjacency[i].size(); ++j) {
                while (cnts[j] < preComp[adjacency[i][j]].size() && included[preComp[adjacency[i][j]][cnts[j]].second]) ++cnts[j];
                if (cnts[j] >= preComp[adjacency[i][j]].size()) continue;
                if (cur == -1 || preComp[adjacency[i][j]][cnts[j]].first > preComp[adjacency[i][cur]][cnts[cur]].first) cur = j;
            }
            if (cur == -1) break;
            preComp[i].emplace_back(preComp[adjacency[i][cur]][cnts[cur]].first + 1, preComp[adjacency[i][cur]][cnts[cur]].second);
            included[preComp[adjacency[i][cur]][cnts[cur]].second] = true;
            modified.push_back(preComp[adjacency[i][cur]][cnts[cur]].second);
            ++cnts[cur];
        }
        while (!modified.empty()) {
            included[modified.back()] = false;
            modified.pop_back();
        }
        preComp[i].push_back({0, i});
    }

    while (q--) {
        int t, y; cin >> t >> y; --t;
        for (int i = 0; i < y; ++i) {
            int city; cin >> city; --city;
            included[city] = true;
            modified.push_back(city);
        }
        if (y <= K || preComp[t].size() <= K) {
            bool done = false;
            for (auto &[distance, city] : preComp[t]) {
                if (!included[city]) {
                    cout << distance << '\n';
                    done = true;
                    break;
                }
            }
            if (!done) cout << -1 << '\n';
        } else {
            vector<int> dp(t + 1, -1); 
            dp[t] = 0;
            for (int i = t; i >= 0; --i) {
                if (dp[i] == -1) continue;
                for (int &a : adjacency[i]) dp[a] = max(dp[a], dp[i] + 1);
            }
            int res = -1;
            for (int i = 0; i <= t; ++i) {
                if (included[i]) continue;
                res = max(res, dp[i]);
            }

            cout << res << '\n';
        }

        while (!modified.empty()) {
            included[modified.back()] = false;
            modified.pop_back();
        }
    }

    return 0;
}

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