Submission #1064583

#	Time	Username	Problem	Language	Result	Execution time	Memory
1064583		onbert	Event Hopping 2 (JOI21_event2)	C++17	100 / 100	136 ms	40992 KiB

event2

#include <bits/stdc++.h>
using namespace std;
#define int long long
const int maxn = 2e5 + 5, lg = 18, INF = 1e18;
int n, k, m;
int st[maxn][lg];

int cnt(int l, int r){
    int val = 0;
    for (int i=lg-1;i>=0;i--) {
        if (st[l][i]<=r) {
            val += (1<<i);
            l = st[l][i];
        }
    }
    return val;
}

signed main() {
    ios::sync_with_stdio(0); cin.tie(0);
    cin >> n >> k;
    vector<int> vals = {-1};
    pair<int,int> a[n];
    for (auto &[x, y]:a) {
        cin >> x >> y;
        vals.push_back(x); vals.push_back(y);
    }
    sort(vals.begin(), vals.end());
    vals.erase(unique(vals.begin(), vals.end()), vals.end());
    m = vals.size() - 1;
    for (int i=1;i<=m;i++) for (int j=0;j<lg;j++) st[i][j] = INF;
    for (auto &[x, y]:a) {
        x = lower_bound(vals.begin(), vals.end(), x) - vals.begin();
        y = lower_bound(vals.begin(), vals.end(), y) - vals.begin();
        st[x][0] = min(y, st[x][0]);
    }
    for (int i=m-1;i>=1;i--) st[i][0] = min(st[i][0], st[i+1][0]);
    for (int i=m-1;i>=1;i--) {
        for (int j=1;j<lg;j++) {
            if (st[i][j-1]==INF) break;
            st[i][j] = st[st[i][j-1]][j-1];
        }
    }
    vector<int> ans;
    set<pair<int, int>> s;
    s.insert({1, 1}); s.insert({m, m});
    int cur = cnt(1, m);
    // cout << cur << endl;
    for (int i=0;i<n && ans.size()<k;i++) {
        auto [l, r] = a[i];
        auto it = s.lower_bound(make_pair(l, r));
        int lhs = prev(it)->second, rhs = it->first;
        if (lhs > l || rhs < r) continue;
        int delta = -cnt(lhs, rhs) + cnt(lhs, l) + cnt(r, rhs);
        if (cur + delta + ans.size() + 1 >= k) {
            ans.push_back(i+1);
            cur += delta;
            s.insert({l, r});
        }
    }
    if (ans.size() < k) cout << "-1\n";
    else {
        for (int i:ans) cout << i << "\n";
    }
}

Compilation message (stderr)

event2.cpp: In function 'int main()':
event2.cpp:49:35: warning: comparison of integer expressions of different signedness: 'std::vector<long long int>::size_type' {aka 'long unsigned int'} and 'long long int' [-Wsign-compare]
   49 |     for (int i=0;i<n && ans.size()<k;i++) {
      |                         ~~~~~~~~~~^~
event2.cpp:55:42: warning: comparison of integer expressions of different signedness: 'long long unsigned int' and 'long long int' [-Wsign-compare]
   55 |         if (cur + delta + ans.size() + 1 >= k) {
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
event2.cpp:61:20: warning: comparison of integer expressions of different signedness: 'std::vector<long long int>::size_type' {aka 'long unsigned int'} and 'long long int' [-Wsign-compare]
   61 |     if (ans.size() < k) cout << "-1\n";
      |         ~~~~~~~~~~~^~~

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