Submission #745810

#	Time	Username	Problem	Language	Result	Execution time	Memory
745810		vjudge1	Event Hopping (BOI22_events)	C++17	0 / 100	42 ms	100652 KiB

events

#include <iostream>
#include <vector>
using namespace std;

struct event {
    int s, e;
};

int n, q, a, b;
vector <event> v(5001);
vector <vector <int>> g(1e5 + 1);
vector <vector <int>> d(5001, vector <int>(5001, 1e9));
vector <bool> done(5001, false);

void dfs(int x) {
    if (done[x]) return;
    done[x] = true;
    for (int i : g[x]) {
        dfs(i);
        for (int j = 1; j <= n; j++) d[x][j] = min(d[x][j], d[i][j] + 1);
    }
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cin >> n >> q;
    if (n > 5000) return 0;
    for (int i = 1; i <= n; i++) {
        cin >> v[i].s >> v[i].e;
        d[i][i] = 0;
    }
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++) {
            if (v[i].e >= v[j].s && v[i].e < v[j].e) g[i].push_back(j);
            if (v[i].e == v[j].e) d[i][j] = 1;
        }
    }
    for (int i = 1; i <= n; i++) dfs(i);
    for (int i = 0; i < q; i++) {
        cin >> a >> b;
        if (d[a][b] < 1e9) cout << d[a][b] << "\n";
        else cout << "impossible\n";
    }
}

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