제출 #721656

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
721656		drdilyor	Event Hopping (BOI22_events)	C++17	0 / 100	1544 ms	7676 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 [l, r, i] : ev) cout << l << ' ' << r << ' ' << i << "\n";

    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;
        }
        //cout << "s,e = " << si << ' '<< ei << '\n';

        int res = 0;
        bool found = 0;
        int left = ev[ei].l;
        set<int> st;
        for (int j = ei-1; j >= 0; j--) {
            auto [l,r,_i] = ev[j];
            if (r < left) {
                if (st.empty()) break;
                left = *st.begin();
                if (r < left) break;
                st.clear();
                res++;
                if (j == si) {found = 1; break;}
            } else if (j == si) {
                res++;
                found = 1;
                break;
            }
            st.insert(l);
        }


        if (found) cout << res << '\n';
        else cout << "impossible\n";
    }

    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

events.cpp: In function 'int main()':
events.cpp:57:18: warning: 'ei' may be used uninitialized in this function [-Wmaybe-uninitialized]
   57 |         for (int j = ei-1; j >= 0; j--) {
      |                  ^

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