Submission #745837

#	Time	Username	Problem	Language	Result	Execution time	Memory
745837		vjudge1	Event Hopping (BOI22_events)	C++14	10 / 100	1579 ms	30332 KiB

events

#include <bits/stdc++.h>

using namespace std;



int main(){

    int n, q;
    cin >> n >> q;
    vector<pair<int, int> > inter(n);


    for (int i = 0; i < n; i++){
        cin >> inter[i].first >> inter[i].second;
    }
    vector<vector<int> > graph(n);

    for (int i = 0; i < n; i++){
        for (int j = 0; j < n; j++){
            if (i == j) continue;
            if (inter[i].second <= inter[j].second && inter[i].second >= inter[j].first){
                graph[i].push_back(j);
            }
        }
    }

    // for (int i = 0; i < n; i++){
    //     for (int x : graph[i]) cout << x << " ";
    //     cout << endl;
    // }

    for (int i = 0; i < q; i++){
        int s, e;
        cin >> s >> e;
        s--, e--;

        queue<int> q;
        q.push(s);
        vector<int> tav(n, -1); 
        tav [s] = 0;
        while(!q.empty()){
            int pos = q.front();
            q.pop();
            for (int x : graph[pos]){
                if (tav[x] == -1){
                    tav[x] = tav[pos] + 1;
                    q.push(x);
                }
            }
        }
        if (tav[e] == -1) {
            cout << "impossible" << endl;
        }
        else cout << tav[e] << endl;
    }


    return 0;
}

/*

5 2
1 3
2 4
4 7
7 9
3 7
1 4
3 2

*/

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