Submission #673966

#	Time	Username	Problem	Language	Result	Execution time	Memory
673966		stanislavpolyn	Event Hopping (BOI22_events)	C++17	45 / 100	1584 ms	14212 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 all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
#define pw(x) (1LL << (x))

using namespace std;

mt19937_64 rng(228);

#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;
pii a[N];

ve<int> order;

int to[N];
int d[N];
ve<pii> Q[N];
int ans[N];
//bool subtask1 = 1;

pii get(int v) {
    if (to[v] == v) {
        return {v, 0};
    } else {
        pii p = get(to[v]);
        p.se += d[v];
        to[v] = p.fi;
        d[v] = p.se;
        return {p.fi, p.se};
    }
}

bool TL() {
    return (double)clock() / CLOCKS_PER_SEC > 1.4;
}

ve<int> st;

bool have[N];
bool subtask = 1;
bool subtask1;

int go[N][20];

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

    cin >> n >> q;

//    subtask1 &= n > 5000 || q > 100;

    ve<int> u;
    fr (i, 1, n) {
        cin >> a[i].fi >> a[i].se;
        order.pb(i);
        u.pb(a[i].se);
    }

    sort(all(u));

    {
        sort(all(order), [](int i, int j) {
            return a[i].fi < a[j].fi || (a[i].fi == a[j].fi && a[i].se > a[j].se);
        });

        fe (i, order) {
            if (sz(st) && a[st.back()].se >= a[i].se) {
                to[i] = st.back();
                continue;
            }
            st.pb(i);
            have[i] = 1;
        }


        fr (i, 1, sz(st) - 1) {
            assert(a[st[i]].fi > a[st[i - 1]].fi);
            assert(a[st[i]].se > a[st[i - 1]].se);
        }

        {
            int mx = -1e9;
            int mxI = -1;
            int ptr = 0;

            fe (i, st) {
                while (ptr < sz(st) && a[st[ptr]].fi <= a[i].se) {
                    if (umx(mx, a[st[ptr]].se)) {
                        mxI = st[ptr];
                    }
                    ptr++;
                }

                if (mx >= a[i].se) {
                    to[i] = mxI;
                } else {
                    assert(0);
                    to[i] = -1;
                }
            }
        }

        subtask &= sz(st) == n;
    }

    if (subtask) {
        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, 1, q) {
            int s, e;
            cin >> s >> e;

            if (s == e) {
                cout << "0\n";
                continue;
            }

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

            int v = s;
            int ans = 0;

            rf (p, 19, 0) {
                if (!go[v][p]) continue;

                int nxt = go[v][p];
                if (a[nxt].se < a[e].se) {
                    v = go[v][p];
                    ans += pw(p);
                }
            }

            while (1) {
                if (a[to[v]].se == a[v].se || a[to[v]].se > a[e].se || a[v].se >= a[e].fi) {
                    break;
                }
                v = to[v];
                ans++;
            }

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

        }


        return 0;
    }

//    fr (i, 1, n) {
//        int p1 = lower_bound(all(u), a[i].fi) - u.begin();
//        int p2 = upper_bound(all(u), a[i].se) - u.begin() - 1;
//        if (max(0, p2 - p1 + 1) > 2) {
//            assert(0);
//        }
//    }

//    fr (i, 1, n) {
//        int cnt = 0;
//        fr (j, 1, n) {
//            if (i == j) continue;
//
//            if (a[j].fi <= a[i].se && a[i].se <= a[j].se) {
//                cnt++;
//            }
//        }
//        assert(cnt <= 1);
//    }

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

        if (s == e) {
            ans[i] = 0;
            continue;
        }

        if (a[s].se >= a[e].fi && a[s].se <= a[e].se) {
            ans[i] = 1;
            continue;
        }

        if (a[s].se > a[e].se) {
            ans[i] = -1;
            continue;
        }
        Q[e].pb({s, i});
    }


    sort(all(order), [](int i, int j) {
        return a[i].se < a[j].se || (a[i].se == a[j].se && a[i].fi < a[j].fi);
    });

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

//    subtask1 = 1;

//    if (q > 100 || n > 5000) {
        subtask1 = 1;
//    }

    ve<pii> add, del;
    fr (idx, 0, sz(order) - 1) {
        int i = order[idx];

        int l = 0;
        int r = idx - 1;
        while (l < r) {
            int mid = l + ((r - l) >> 1);
            int j = order[mid];

            if (a[j].se < a[i].fi) {
                l = mid + 1;
            } else {
                r = mid;
            }
        }

        if (a[order[l]].se < a[i].fi) {
            l++;
        }

        if (l <= idx - 1) {

//            rf (ptr, idx - 1, l) {
//                int j = order[ptr];
//                to[j] = i;
//                d[j] = 1;
//            }

            add.pb({l, idx});
            del.pb({idx, idx});
        }

//        rf (ptr, idx - 1, 0) {
//            int j = order[ptr];
//            if (a[j].se < a[i].fi) {
//                break;
//            }
//
//            subtask1 &= ptr == idx - 1;
//            to[j] = i;
//            d[j] = 1;
//        }

        if (sz(Q[i])) {
            sort(all(add));
            sort(all(del));
//
            int ptr1 = 0;
            int ptr2 = 0;
            set<int> s;
            fr (cur, 0, idx) {
                while (ptr1 < sz(add) && add[ptr1].fi <= cur) {
                    s.insert(add[ptr1].se);
                    ptr1++;
                }
                while (ptr2 < sz(del) && del[ptr2].fi <= cur) {
                    s.erase(del[ptr2].se);
                    ptr2++;
                }

                int i = order[cur];

                if (sz(s)) {
                    d[i] = 1;
//                    assert(to[i] == order[*s.rbegin()]);
                    to[i] = order[*s.rbegin()];
                }
            }

            add.clear();
            del.clear();
        }

        fe (cur, Q[i]) {
            if (subtask1) {
                auto p = get(cur.fi);

                if (p.fi == i) {
                    ans[cur.se] = p.se;
                } else {
                    ans[cur.se] = -1;
                }
            } else {
                int v = cur.fi;
                int sum = 0;
                while (to[v] != v) {
                    sum += d[v];
                    v = to[v];
                }

                if (v == i) {
                    ans[cur.se] = sum;
                } else {
                    ans[cur.se] = -1;
                }
            }
        }
    }

    fr (i, 1, q) {
        if (ans[i] == -1) {
            cout << "impossible\n";
        } else {
            cout << ans[i] << "\n";
        }
    }

    return 0;
}

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