Submission #674499

#	Time	Username	Problem	Language	Result	Execution time	Memory
674499		stanislavpolyn	Event Hopping (BOI22_events)	C++17	100 / 100	183 ms	17200 KiB

events

#include <bits/stdc++.h>

#define fr(i, a, b) for (int i = (a); i <= (b); i++)
#define rf(i, a, b) for (int i = (a); i >= (b); i--)
#define fe(x, y) for (auto& x : y)

#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define mt make_tuple

#define pw(x) (1LL << (x))
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()

using namespace std;

mt19937_64 rng(chrono::system_clock::now().time_since_epoch().count());

#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template <typename T>
using oset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define fbo find_by_order
#define ook order_of_key

template <typename T>
bool umn(T& a, T b) {
    return a > b ? a = b, 1 : 0;
}
template <typename T>
bool umx(T& a, T b) {
    return a < b ? a = b, 1 : 0;
}

using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template <typename T>
using ve = vector<T>;

const int N = 1e5 + 5;

int n, q;
ve<pii> a;
int to[N];

int go[N][20];

ve<int> u;

pii t[4 * N];

void upd(int v, int tl, int tr, int pos, int val, int idx) {
    if (tl == tr) {
        umn(t[v], mp(val, idx));
        return;
    }
    int tm = (tl + tr) >> 1;
    if (pos <= tm) upd(v << 1, tl, tm, pos, val, idx);
    else upd(v << 1 | 1, tm + 1, tr, pos, val, idx);
    t[v] = min(t[v << 1], t[v << 1 | 1]);
}

void upd(int pos, int val, int idx) {
    upd(1, 0, sz(u) - 1, pos, val, idx);
}

pii get(int v, int tl, int tr, int l, int r) {
    if (l > r) {
        return mp(int(1e9), 0);
    }
    if (tl == l && tr == r) {
        return t[v];
    }
    int tm = (tl + tr) >> 1;
    return min(get(v << 1, tl, tm, l, min(r, tm)),
               get(v << 1 | 1, tm + 1, tr, max(tm + 1, l), r));
}

pii get(int l, int r) {
    return get(1, 0, sz(u) - 1, l, r);
}

int main() {
#ifndef LOCAL
    // freopen("input.txt", "r", stdin);
    // freopen("output.txt", "w", stdout);
    ios::sync_with_stdio(0);
    cin.tie(0);
#else
    // freopen("input.txt", "r", stdin);
    // freopen("output.txt", "w", stdout);
#endif

    cin >> n >> q;
    a.resize(n + 1);
    fr (i, 1, n) {
        cin >> a[i].fi >> a[i].se;
        // to[i] = i;

        u.pb(a[i].se);
    }

    sort(all(u));
    u.erase(unique(all(u)), u.end());

    fill(t, t + 4 * N, mp(int(1e9), 0));

    fr (i, 1, n) {
        int id = lower_bound(all(u), a[i].se) - u.begin();
        upd(id, a[i].fi, i);
    }

    fr (i, 1, n) {
        int L = lower_bound(all(u), a[i].fi) - u.begin();
        int R = upper_bound(all(u), a[i].se) - u.begin() - 1;
        to[i] = get(L, R).se;
    }

    // fr (i, 1, n) {
    //     fr (j, 1, n) {
    //         if (i == j) continue;

    //         if (a[j].se >= a[i].fi && a[j].se <= a[i].se) {
    //             if (!to[i] || a[to[i]].fi > a[j].fi) {
    //                 to[i] = j;
    //             }
    //         }
    //     }
    // }

    fr (i, 1, n) {
        go[i][0] = to[i];
    }

    fr (p, 1, 19) {
        fr (i, 1, n) {
            go[i][p] = go[go[i][p - 1]][p - 1];
        }
    }

    fr (i, 0, q - 1) {
        int s, e;
        cin >> s >> e;

        if (a[s].se > a[e].se) {
            cout << "impossible\n";
            continue;
        }
        if (s == e) {
            cout << "0\n";
            continue;
        }

        int v = e;
        int ans = 0;
        rf (p, 19, 0) {
            if (go[v][p] && a[go[v][p]].fi > a[s].se) {
                ans += pw(p);
                v = go[v][p];
            }
        }

        if (to[v] && a[v].fi > a[s].se) {
            v = to[v];
            ans++;
        }

        if (a[v].fi <= a[s].se) {
            ans++;
            cout << ans << "\n";
        } else {
            cout << "impossible\n";
        }
    }

    return 0;
}

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