Submission #721845

#	Time	Username	Problem	Language	Result	Execution time	Memory
721845		drdilyor	Event Hopping (BOI22_events)	C++17	25 / 100	699 ms	524288 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 ? a.l < b.l : a.r < b.r ;
    });
    //for (auto[a,b,c] : ev) cout << a << ' ' << b << ' ' << c <<'\n';
 
    vector ans(n, vector(n, inf));

    vector<int> mnl(k, inf);
    for (auto [l, r, i] :ev) {
        mnl[r] = min(mnl[r], l);
    }

    for (int ei = n-1; ei >= 0; ei--) {
        int res = 0;
        int lb = ev[ei].l, rb = ev[ei].r;
        for (int j = n-1; j >= 0; j--) {
            auto [l,r,_i] = ev[j];
            if (r > ev[ei].r) continue;
            if (r < lb) {
                int mn = inf;
                for (int i = lb; i <= rb; i++)
                    mn = min(mn, mnl[i]);
                lb = mn;
                if (r < lb) break;
                rb = r;
                res++;
            }
            ans[ei][j] = res + 1;
        }
    }

    while (m--) {
        int s, e;
        cin >> s >> e;
        s--;e--;
 
        if (s == e) {
            cout << "0\n";
            continue;
        }

        int si = 0, ei = 0;
        for (int j = 0; j < n; j++) {
            if (ev[j].i == s) si = j;
            if (ev[j].i == e) ei = j;
        }
 
        if (ans[ei][si] < inf) cout << ans[ei][si] << '\n';
        else cout << "impossible\n";
    }
 
    return 0;
}

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