Submission #779556

#	Time	Username	Problem	Language	Result	Execution time	Memory
779556		CpDark	Event Hopping (BOI22_events)	C++14	30 / 100	114 ms	19752 KiB

events

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int, int> pii;
typedef vector<pii> vp;
typedef vector<vp> vvp;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<ll> vll;
typedef vector<vll> vvll;

const ll inf = 1e18 + 7;

vvp table;
vp events;
vector<pair<int,pii>> endTimes;
int mylog;

int query(int start, int end) {
    if (events[start].second > events[end].second)return -1;
    if (start == end)return 0;
    int wall = events[start].second;
    int jumps = 0;
    
    for (int i = mylog;i >= 0;i--) {
        if (table[i][end].second > wall) {
            jumps += 1 << i;
            end = table[i][end].first;
        }
    }
    jumps++;
    end = table[0][end].first;
    if (events[end].second <= wall && events[start].first >= events[end].first)return jumps;
    return -1;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int n, q;
    cin >> n >> q;
    mylog = ceil(log2(n + 1));
    events.resize(n);
    endTimes.resize(n);
    table.resize(mylog + 1, vp(n));
    
    for (int i = 0;i < n;i++) {
        cin >> events[i].first >> events[i].second;
        endTimes[i] = { events[i].second, {events[i].first, i} };
    }
 
    sort(endTimes.begin(), endTimes.end());
 
    for (int i = 0;i < endTimes.size();i++) {
        int index = endTimes[i].second.second;
        int far = lower_bound(endTimes.begin(), endTimes.end(), (pair<int, pii>){ events[index].first, make_pair(-1,-1)}) - endTimes.begin();
        table[0][index] = { endTimes[far].second.second, endTimes[far].first};
    }
 
    for (int i = 1;i <= mylog;i++) {
        for (int v = 0;v < n;v++) {
            int p = table[i - 1][v].first;
            table[i][v] = table[i - 1][p];
        }
    }
 
    int s, e;
    for (int i = 0;i < q;i++) {
        cin >> s >> e;
        s--; e--;
        int ans = query(s, e);
        if (ans == -1) {
            cout << "impossible\n";
        }
        else {
            cout << ans << '\n';
        }
    }
 
    return 0;
}

Compilation message (stderr)

events.cpp: In function 'int main()':
events.cpp:58:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, std::pair<int, int> > >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   58 |     for (int i = 0;i < endTimes.size();i++) {
      |                    ~~^~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 15
• Subtask 4: 0 / 15
• Subtask 5: 20 / 20
• Subtask 6: 0 / 30