Submission #494829

#	Time	Username	Problem	Language	Result	Execution time	Memory
494829		blue	Event Hopping 2 (JOI21_event2)	C++17	100 / 100	326 ms	43536 KiB

event2

#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <cassert>
#include <algorithm>
using namespace std;

const int mx = 200'000;
const int INF = 1'000'000'001;

const int lg = 19;

using vi = vector<int>;
using pii = pair<int, int>;
#define sz(x) int(x.size())

int jmp[1+mx+1][1+lg];

int query(int L, int R) //
{
    // cerr << "\n\n";
    // cerr << "query: " << L << ' ' << R << '\n';
    int ans = 0;
    for(int e = lg; e >= 0; e--)
    {
        if(jmp[L][e] <= R)
        {
            ans += (1 << e);
            L = jmp[L][e];
            if(L >= R) return ans;
        }
    }
    // cerr << "returning " << ans << "\n";
    return ans;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int N, K;
    cin >> N >> K;

    set<int> V;

    int L[1+N], R[1+N];
    for(int i = 1; i <= N; i++)
    {
        cin >> L[i] >> R[i];
        V.insert(L[i]);
        V.insert(R[i]);
    }

    map<int, int> mp;

    int ct = 0;
    for(int v: V) mp[v] = ++ct;
    // cerr << "normalized\n";

    // for(auto y: mp) cerr << y.first << " : " << y.second << '\n';

    for(int i = 1; i <= N; i++)
    {
        L[i] = mp[L[i]];
        R[i] = mp[R[i]];

        // cerr << L[i] << ' ' << R[i] << '\n';
    }
    // cerr << "\n\n";


    vi jmp_val(2+mx, 1+mx);
    jmp_val[mx+1] = mx+1;
    for(int i = 1; i <= N; i++) jmp_val[L[i]] = min(jmp_val[L[i]], R[i]);
    for(int p = mx; p >= 1; p--) jmp_val[p] = min(jmp_val[p], jmp_val[p+1]);

    for(int i = 1; i <= mx+1; i++)
        jmp[i][0] = jmp_val[i];

    for(int e = 1; e <= lg; e++)
    {
        for(int i = 1; i <= mx+1; i++)
        {
            jmp[i][e] = jmp[jmp[i][e-1]][e-1];
        }
    }

            // jmp[i][e] = jmp[ jmp[i][e-1] ][e-1];

    int max_events = query(1, mx);

    if(max_events < K)
    {
        cout << "-1\n";
        return 0;
    }

    // cerr << "max events = " << max_events << '\n';

    vi res;

    set<pii> events;
    events.insert({1, 1});
    events.insert({mx, mx});


    // for(int i = 1; i <= 20; i++) cerr << jmp_val[i] << ' ';
    // cerr << '\n';





    for(int i = 1; i <= N && sz(res) < K; i++)
    {
        auto y2 = events.lower_bound({L[i], R[i]});

        if(R[i] > y2->first) continue;

        auto y1 = y2;
        y1--;

        if(L[i] < y1->second) continue;

        int change = query(y1->second, L[i]) + query(R[i], y2->first) + 1 - query(y1->second, y2->first);
        if(max_events + change < K) continue;

        max_events += change;
        events.insert({L[i], R[i]});
        res.push_back(i);
    }

    for(int r: res) cout << r << '\n';
    // cout << '\n';
}

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