Submission #721606

#	Time	Username	Problem	Language	Result	Execution time	Memory
721606		drdilyor	Event Hopping (BOI22_events)	C++17	0 / 100	1540 ms	12336 KiB

events

#include<bits/stdc++.h>
using namespace std;
using ll = long long;


const int inf = 1e9 + 1e5;
struct event {
    int l, r, i;
};

int main() {
    int n, m;
    cin >> n >> m;
    vector<event> ev(n), og;
    map<int,int> comp;
    int _i = 0;
    for (auto& [s, e, i] : ev) {
        cin >> s >> e;
        comp[s] = comp[e] = 0;
        i = _i++;
    }
    int k = 0;
    for (auto& mp : comp)
        mp.second = k++;
    for (auto& [s, e, i] : ev)
        s = comp[s], e = comp[e];

    og = ev;
    sort(ev.begin(), ev.end(), [&](auto& a, auto& b) {
        return a.r < b.r;
    });

    while (m--) {
        int s, e;
        cin >> s >> e;
        s--;e--;

        if (s == e) {
            cout << "0\n";
            continue;
        }


        int si = 0, ei;
        for (int j = 0; j < n; j++) {
            if (ev[j].i == s) si = j;
            if (ev[j].i == e) ei = j;
        }
        vector memo(n+1, -1);
        auto dp = [&](auto& dp, int i)->int{
            int t = ev[i].r;
            if (i == ei) return 0;
            if (t > ev[ei].r) return inf;
            if (memo[i]!=-1) return memo[i];
            int res = inf;
            for (int j = i+1; j < n; j++) {
                if (ev[j].l <= t && t <= ev[j].r)
                    res = min(res, 1 + dp(dp, j));
            }
            return memo[i] = res;
        };
        int res = dp(dp, si);
        if (res < inf) cout << res << '\n';
        else cout << "impossible\n";
    }

    return 0;
}

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