Submission #425260

#	Time	Username	Problem	Language	Result	Execution time	Memory
425260		Osama_Alkhodairy	Event Hopping 2 (JOI21_event2)	C++17	100 / 100	400 ms	29064 KiB

event2

#include <bits/stdc++.h>
using namespace std;
#define finish(x) return cout << x << endl, 0
#define ll long long

const int N = 100001;
const int K = 20;
const int INF = (int)1e9;

int n, k, nxt[N][K];
pair <int, int> tree[4 * N];
vector <pair <int, int> > a;

void update(int idx){
    int p = a[idx].first + 2 * n;
    tree[p] = min(tree[p], make_pair(a[idx].second, idx));
    for(; p > 1 ; p >>= 1){
        tree[p >> 1] = min(tree[p], tree[p ^ 1]);
    }
}
pair <int, int> query(int l, int r){
    r++;
    auto ret = make_pair(INF, INF);
    for(l += 2 * n, r += 2 * n ; l < r ; l >>= 1, r >>= 1){
        if(l & 1) ret = min(ret, tree[l++]);
        if(r & 1) ret = min(ret, tree[--r]);
    }
    return ret;
}
int calc(int l, int r){
    if(r < l) return 0;
    int idx = query(l, r).second;
    if(idx == INF) return 0;
    if(a[idx].second > r) return 0;
    int ret = 1;
    for(int i = K - 1 ; i >= 0 ; i--){
        if(nxt[idx][i] == INF) continue;
        if(a[nxt[idx][i]].second > r) continue;
        ret += (1 << i);
        idx = nxt[idx][i];
    }
    return ret;
}
int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    for(int i = 0 ; i < 4 * N ; i++){
        tree[i] = make_pair(INF, INF);
    }
    cin >> n >> k;
    a.resize(n);
    for(auto &i : a) cin >> i.first >> i.second;
    map <int, int> mp;
    for(auto &i : a) mp[i.first], mp[i.second];
    int x = 0;
    for(auto &i : mp) i.second = x++;
    for(auto &i : a){
        i.first = mp[i.first];
        i.second = mp[i.second];
    }
    for(int i = 0 ; i < n ; i++){
        update(i);
    }
    for(int i = 0 ; i < n ; i++){
        nxt[i][0] = query(a[i].second, 2 * n - 1).second;
    }
    vector <int> all;
    for(int i = 0 ; i < n ; i++){
        all.push_back(i);
    }
    sort(all.begin(), all.end(), [&](int l, int r){
        return a[l].first > a[r].first;
    });
    for(auto &i : all){
        for(int k = 1 ; k < K ; k++){
            if(nxt[i][k - 1] == INF) nxt[i][k] = INF;
            else nxt[i][k] = nxt[nxt[i][k - 1]][k - 1];
        }
    }
    set <pair <int, int> > cur;
    cur.insert(make_pair(0, 2 * n - 1));
    int cnt = calc(0, 2 * n - 1);
    if(cnt < k) finish(-1);
    vector <int> res;
    for(int i = 0 ; i < n ; i++){
        auto it = cur.upper_bound(make_pair(a[i].first, INF));
        it--;
        if(!(it->first <= a[i].first && a[i].second <= it->second)) continue;
        cnt -= calc(it->first, it->second);
        if(cnt + (int)res.size() + 1 + calc(it->first, a[i].first) + calc(a[i].second, it->second) < k){
            cnt += calc(it->first, it->second);
            continue;
        }
        res.push_back(i);
        cur.insert(make_pair(it->first, a[i].first));
        cnt += calc(it->first, a[i].first);
        cur.insert(make_pair(a[i].second, it->second));
        cnt += calc(a[i].second, it->second);
        cur.erase(it);
    }
    while((int)res.size() > k) res.pop_back();
    assert((int)res.size() == k);
    for(auto &i : res) cout << i + 1 << "\n";
}

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