Submission #714239

#	Time	Username	Problem	Language	Result	Execution time	Memory
714239		vjudge1	Event Hopping (BOI22_events)	C++17	10 / 100	1582 ms	130200 KiB

events

#include <iostream>
#include <vector>
#include <queue>
using namespace std;
int n, q;
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cin >> n >> q;
    vector<int>g[n + 1];
    pair<int, int>events[n + 1];
    for(int i = 1;i <= n;++i){
        cin >> events[i].first >> events[i].second;
    }
    for(int i = 1;i <= n;++i){
        for(int j = 1;j <= n;++j){
            if(i == j)continue;
            if(events[i].second >= events[j].first && events[i].second <= events[j].second){
                g[i].push_back(j);
            }
        }
    }
//    for(int i = 1;i <= n;++i){
//        cout << i << ": ";
//        for(int j : g[i]){
//            cout << j << " ";
//        }
//        cout << '\n';
//    }
    vector<pair<int, int>>queries;
    while(q--){
        int u, v;
        cin >> u >> v;
        queries.push_back({u, v});
    }
    vector<vector<int>>dists(n + 1, vector<int>(n + 1, -1));
    bool check[n + 1];
    for(int i = 1;i <= n;++i)check[i] = 0;
    for(pair<int, int>query: queries){
        int u = query.first, v = query.second;
        if(dists[u][v] != -1)cout << dists[u][v] << '\n';
        else if(dists[u][v] == -1 && check[u])cout << "impossible\n";
        else{
            queue<int>que;
            que.push(u);
            check[u] = 1;
            dists[u][u] = 0;
            while(!que.empty()){
                int cur = que.front();
                que.pop();
                for(int vv : g[cur]){
                    if(dists[u][vv] == -1){
                        dists[u][vv] = dists[u][cur] + 1;
                        que.push(vv);
                    }
                }
            }
            if(dists[u][v] == -1)cout << "impossible\n";
            else cout << dists[u][v] << '\n';
        }
    }
}

• Subtask 1: 0 / 10
• Subtask 2: 10 / 10
• Subtask 3: 0 / 15
• Subtask 4: 0 / 15
• Subtask 5: 0 / 20
• Subtask 6: 0 / 30