Submission #589295

#	Time	Username	Problem	Language	Result	Execution time	Memory
589295		1zaid1	Event Hopping (BOI22_events)	C++17	10 / 100	1577 ms	3048 KiB

events

 #include <bits/stdc++.h>
using namespace std;
#define endl '\n'

const int M = 2e5+2;
struct rng {int l, r, i;};
int nxt[M];

signed main() {
    cin.tie(0)->sync_with_stdio(0);

    int n, q;
    cin >> n >> q;

    vector<rng> v(n);
    for (auto &[l, r, i]:v) cin >> l >> r;
    for (int i = 0; i < n; i++) v[i].i = i;

    for (auto [l, r, i]:v) {
        int mn = l, ind = -1;
        for (auto [a, b, j]:v) {
            if (i == j) continue;
            if (a < mn && l <= b && b <= r) {
                ind = j;
                mn = a;
            }
        }

        nxt[i] = ind;
    }

    bitset<100005> vis;
    while (q--) {
        int a, b;
        cin >> a >> b; a--; b--;
        if (a == b) {
            cout << 0 << endl;
            continue;
        }

        int ans = 1;
        auto tmp = v[b];
        while (v[a].r < tmp.l) {
            if (nxt[tmp.i] < 0) break;
            tmp = v[nxt[tmp.i]];
            ans++;
        }

        if (tmp.l <= v[a].r && v[a].r <= tmp.r) {
            cout << ans << endl;
        } else {
            cout << "impossible" << endl;
        }
    }

    return 0;
}
/*
8 5
1 2
3 4
1 5
6 7
5 10
10 20
15 20
999999999 1000000000
1 6
1 7
2 4
3 3
5 8

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