Submission #727868

#	Time	Username	Problem	Language	Result	Execution time	Memory
727868		Charizard2021	Event Hopping (BOI22_events)	C++17	100 / 100	369 ms	26192 KiB

events

#include <bits/stdc++.h>
using namespace std;
int main() {
    int n, q;
    cin >> n >> q;
    vector<vector<int> > dp(17, vector<int>(n));
    vector<vector<pair<int, int> > > sparseTables(17, vector<pair<int, int> >(n, make_pair(1000000001, -1)));
    vector<pair<int, int> > a(n);
    vector<int> b;
    for (int i = 0; i < n; i++) {
        cin >> a[i].first >> a[i].second;
        b.push_back(a[i].second);
    }
    sort(b.begin(), b.end());
    b.erase(unique(b.begin(), b.end()), b.end());
    for (int i = 0; i < n; i++) {
        int right = lower_bound(b.begin(), b.end(), a[i].second) - b.begin();
        sparseTables[0][right] = min(sparseTables[0][right], make_pair(a[i].first, i));
    }
    for (int i = 0; i + 1 < 17; i++){
        for (int j = 0; j + (1 << (i + 1)) <= n; j++){
            sparseTables[i + 1][j] = min(sparseTables[i][j], sparseTables[i][j + (1 << i)]);
        }
    }
    for (int i = 0; i < n; i++){
        int left = lower_bound(b.begin(), b.end(), a[i].first) - b.begin();
        int right = lower_bound(b.begin(), b.end(), a[i].second) - b.begin();
        int h = 31 - __builtin_clz(right - left + 1);
        dp[0][i] = min(sparseTables[h][left], sparseTables[h][right + 1 - (1 << h)]).second;
    }
    for (int i = 0; i + 1 < 17; i++){
        for (int j = 0; j < n; j++){
            dp[i + 1][j] = dp[i][dp[i][j]];
        }
    }
    while (q--) {
        int x, y;
        int left = 1;
        cin >> x >> y;
        x--;
        y--;
        if (x == y || (a[y].first <= a[x].second && a[x].second <= a[y].second)) {
            cout << (x == y ? 0 : 1) << "\n";
            continue;
        }
        for (int i = 17 - 1; ~i; i--) {
            if (a[x].second < a[dp[i][y]].first){
                left += 1 << i, y = dp[i][y];
            }
        }
        y = dp[0][y];
        if (a[x].second < a[y].first || a[x].second > a[y].second){
            cout << "impossible\n";
        }
        else{
            cout << left + (a[x].second >= a[y].first) << "\n";
        }
    }
}

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