Submission #893433

#	Time	Username	Problem	Language	Result	Execution time	Memory
893433		vjudge1	Event Hopping 2 (JOI21_event2)	C++17	8 / 100	60 ms	23368 KiB

event2

#include <bits/stdc++.h>

using namespace std;

#define all(x) x.begin(), x.end()
#define ar array
#define pb push_back
#define ln '\n'
#define int long long

using i64 = long long;

template <class F, class _S>
bool chmin(F &u, const _S &v){
    bool flag = false;
    if ( u > v ){
        u = v; flag |= true;
    }
    return flag;
}

template <class F, class _S>
bool chmax(F &u, const _S &v){
    bool flag = false;
    if ( u < v ){
        u = v; flag |= true;
    }
    return flag;
}

signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, k; cin >> n >> k;
    vector <int> L(n), R(n);
    for ( int i = 0; i < n; i++ ){
        cin >> L[i] >> R[i];
    }
    { // compression
        vector <int> p_;
        for ( int i = 0; i < n; i++ ){
            p_.pb(L[i]);
            p_.pb(R[i]);
        }
        sort(all(p_));
        p_.resize(unique(all(p_)) - p_.begin());
        auto get = [&](int x){
            return lower_bound(all(p_), x) - p_.begin() + 1;
        };
        for ( int i = 0; i < n; i++ ){
            L[i] = get(L[i]);
            R[i] = get(R[i]);
        }
    }
    int m = n * 2;
    vector <vector<int>> quL(m + 1), quR(m + 1);
    for ( int i = 0; i < n; i++ ){
        quR[R[i]].pb(L[i]);
        quL[L[i]].pb(R[i]);
    }
    vector <int> dpL(m + 2), dpR(m + 1);
    for ( int i = m; i > 0; i-- ){
        dpL[i] = dpL[i + 1];
        for ( auto &j: quL[i] ){
            chmax(dpL[i], dpL[j] + 1);
        }
    }
    for ( int i = 1; i <= m; i++ ){
        dpR[i] = dpR[i - 1];
        for ( auto &j: quR[i] ){
            chmax(dpR[i], dpR[j] + 1);
        }
    }
    if ( dpL[1] < k ){
        return cout << "-1\n", 0;
    }
    if ( n > 3e3 ){
        int lst = -1;
        for ( int i = 0; i < n && k > 0; i++ ){
            if ( lst <= L[i] && dpL[R[i]] >= k - 1 ){
                cout << i + 1 << ln;
                k--; lst = R[i];
            }
        } exit(0);
    }
    vector <ar<int,2>> rng;
    rng.pb({1, m});
    int tot = 0;
    for ( int i = 0; i < n && tot < k; i++ ){
        if ( dpR[L[i]] + dpL[R[i]] + 1 < k ){
            continue;
        }
        int it = 0, j = -1;
        for ( auto &[l, r]: rng ){
            if ( l <= L[i] && r >= R[i] ){
                j = it;
            }
            it++;
        }
        if ( j != -1 ){
            cout << i + 1 << ln;
            tot++;
            auto [l, r] = rng[j];
            rng[j] = {l, L[i]};
            rng.pb({R[i], r});
        }
    }

    cout << '\n';
}

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