Submission #1279183

#	Time	Username	Problem	Language	Result	Execution time	Memory
1279183		duckindog	Event Hopping 2 (JOI21_event2)	C++20	32 / 100	29 ms	8804 KiB

event2

#include <bits/stdc++.h>

using namespace std;

const int N = 100'000 + 10;
int n, k;
pair<int, int> p[N];
vector<int> rrh;

namespace ST { 
    int f[N][17];
    void init() { 
        for (int i = 1; i <= (int)rrh.size() + 1; ++i) { 
            for (int j = 0; j <= 16; ++j) f[i][j] = rrh.size() + 1;
        }
        for (int i = 1; i <= n; ++i) { 
            const auto& [x, y] = p[i];
            f[x][0] = min(f[x][0], y);
        }
        for (int i = rrh.size(); i >= 1; --i) { 
            for (int j = 0; j <= 16; ++j) { 
                auto& ret = f[i][j];
                ret = min(ret, f[i + 1][j]);
                if (j) ret = min(ret, f[f[i][j - 1]][j - 1]);
            }
        }
    }
    int get(int l, int r) { 
        int ret = 0;
        for (int i = 16; i >= 0; --i) { 
            if (f[l][i] <= r) { 
                ret += (1 << i);
                l = f[l][i];
            }
        }
        return ret;
    }
}

int32_t main() { 
    cin.tie(0)->sync_with_stdio(0);

    cin >> n >> k;
    for (int i = 1; i <= n; ++i) cin >> p[i].first >> p[i].second;

    for (int i = 1; i <= n; ++i) { 
        rrh.push_back(p[i].first);
        rrh.push_back(p[i].second);
    }
    sort(rrh.begin(), rrh.end());
    rrh.erase(unique(rrh.begin(), rrh.end()), rrh.end());

    for (int i = 1; i <= n; ++i) { 
        auto& [x, y] = p[i];
        x = upper_bound(rrh.begin(), rrh.end(), x) - rrh.begin();
        y = upper_bound(rrh.begin(), rrh.end(), y) - rrh.begin();
    }

    ST::init();

    int total = ST::get(1, rrh.size());
    if (total < k) { 
        cout << -1 << '\n';
        return 0;
    }

    int cnt = 0;

    set<pair<int, int>> s{{1, rrh.size()}};
    for (int i = 1; i <= n; ++i) { 
        const auto& [x, y] = p[i];

        int l = -1, r = -1;

        bool isValid = true;
        { // check if intersect
            auto it = s.lower_bound({x + 1, 0});
            if (it == s.begin()) isValid = false;
            else { 
                it = prev(it);
                if (it->second < y) isValid = false;
                tie(l, r) = *it;
            }
        }
        if (!isValid) continue;
        
        int nTotal = total - ST::get(l, r) + ST::get(l, x) + ST::get(y, r) + 1;
        if (nTotal < k) continue;

        s.erase({l, r});
        if (l < x) s.insert({l, x});
        if (y < r) s.insert({y, r});
        total = nTotal;

        cout << i << "\n";

        if (++cnt == k) break;
    }
}

• Subtask 1: 0 / 7
• Subtask 2: 1 / 1
• Subtask 3: 31 / 31
• Subtask 4: 0 / 61