Submission #838642

#	Time	Username	Problem	Language	Result	Execution time	Memory
838642		skittles1412	Event Hopping (BOI22_events)	C++17	0 / 100	1594 ms	8148 KiB

events

#include "bits/extc++.h"

using namespace std;

template <typename T, typename... U>
void dbgh(const T& t, const U&... u) {
    cerr << t;
    ((cerr << " | " << u), ...);
    cerr << endl;
}

#ifdef DEBUG
#define dbg(...)                                              \
    cerr << "L" << __LINE__ << " [" << #__VA_ARGS__ << "]: "; \
    dbgh(__VA_ARGS__)
#else
#define dbg(...)
#define cerr   \
    if (false) \
    cerr
#endif

#define endl "\n"
#define long int64_t
#define sz(x) int(std::size(x))

struct ST {
    int n, logn;
    vector<vector<int>> v;

    ST(const vector<int>& arr) : n(sz(arr)), v(__lg(n) + 1, vector<int>(n)) {
        v[0] = arr;
        for (int i = 1; i <= logn; i++) {
            for (int j = 0; j + (1 << i) <= n; j++) {
                v[i][j] = min(v[i - 1][j], v[i - 1][j + (1 << (i - 1))]);
            }
        }
    }

    int query(int l, int r) const {
        int k = __lg(r - l);
        return min(v[k][l], v[k][r - (1 << k)]);
    }
};

void solve() {
    int n, q;
    cin >> n >> q;

    vector<pair<int, int>> arr(n);
    for (auto& [l, r] : arr) {
        cin >> l >> r;
    }

    int logn = __lg(n);
    vector<vector<int>> lift(logn + 1, vector<int>(n));

    for (int i = 0; i < n; i++) {
        pair<int, int> opt {-1, -1};

        for (int j = 0; j < n; j++) {
            if (arr[j].first <= arr[i].second &&
                arr[i].second <= arr[j].second) {
                opt = max(opt, {arr[j].second, j});
            }
        }

        if (opt.first == arr[i].second) {
            lift[0][i] = -1;
        } else {
            lift[0][i] = opt.second;
        }
    }

    for (int i = 1; i <= logn; i++) {
        for (int j = 0; j < n; j++) {
            if (lift[i - 1][j] == -1) {
                lift[i][j] = -1;
            } else {
                lift[i][j] = lift[i - 1][lift[i - 1][j]];
            }
        }
    }

    int qans[q];
    map<int, vector<array<int, 4>>> evts;

    for (int qi = 0; qi < q; qi++) {
        int u, v;
        cin >> u >> v;
        u--;
        v--;

        if (u == v) {
            qans[qi] = 0;
            continue;
        }

        int ans = 0;

        for (int i = logn; i >= 0; i--) {
            int nu = lift[i][u];

            if (nu != -1 && arr[nu].second < arr[v].first) {
                u = nu;
                ans += 1 << i;
            }
        }

        // int pos = arr[u].second, ans = 0;

        // while (pos < arr[v].first) {
        //     int n_pos = -1;

        //     for (auto& [l, r] : arr) {
        //         if (l <= pos && pos <= r && r <= arr[v].second) {
        //             n_pos = max(n_pos, r);
        //         }
        //     }

        //     if (n_pos == -1 || pos == n_pos) {
        //         break;
        //     }
        //     pos = n_pos;
        //     ans++;
        // }

        int pos = arr[u].second;
        if (pos < arr[v].first) {
            evts[pos].push_back({arr[v].first, arr[v].second, qi, ans});
            for (auto& [l, r] : arr) {
                if (l <= pos && arr[v].first <= r && r <= arr[v].second) {
                    pos = r;
                    ans++;
                    break;
                }
            }
            if (arr[v].first <= pos && pos <= arr[v].second) {
                ans++;
                qans[qi] = ans;
            } else {
                qans[qi] = -1;
            }
        } else {
            if (arr[v].first <= pos && pos <= arr[v].second) {
                ans++;
                qans[qi] = ans;
            } else {
                qans[qi] = -1;
            }
        }
    }

    for (auto& a : qans) {
        if (a == -1) {
            cout << "impossible" << endl;
        } else {
            cout << a << endl;
        }
    }
}

int main() {
    cin.tie(nullptr);
    cin.exceptions(ios::failbit);
    ios_base::sync_with_stdio(false);
    solve();
}

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