Submission #935664

#	Time	Username	Problem	Language	Result	Execution time	Memory
935664		peterandvoi	Event Hopping (BOI22_events)	C++17	100 / 100	136 ms	13684 KiB

events

#include <bits/stdc++.h>

using namespace std;

#ifdef ngu
#include "debug.h"
#else
#define debug(...) 42
#endif

#define MASK(x) (1LL << (x))

const int N = (int) 1e5 + 5;
const int LOG = 17;

int n, m, q;
pair<int, int> event[N];
int up[LOG][N];

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    #ifdef ngu
    freopen("test.inp", "r", stdin);
    freopen("test.out", "w", stdout);
    #endif
    cin >> n >> q;
    vector<int> R;
    for (int i = 1; i <= n; ++i) {
        cin >> event[i].first >> event[i].second;
        R.emplace_back(event[i].second);
    }
    auto cmb = [&](int x, int y) {
        if (x == -1) {
            return y;
        }
        if (y == -1) {
            return x;
        }
        return event[x].first < event[y].first ? x : y;
    };
    sort(R.begin(), R.end());
    R.erase(unique(R.begin(), R.end()), R.end());
    m = (int) R.size();
    vector<int> tree(4 << __lg(m), -1);
    auto upd = [&](int i, int x) {
        int id = 1, l = 1, r = m;
        while (l < r) {
            int mid = l + r >> 1;
            id <<= 1;
            if (i <= mid) {
                r = mid;
            } else {
                id |= 1;
                l = mid + 1;
            }
        }
        tree[id] = cmb(tree[id], x);
        while (id > 1) {
            id >>= 1;
            tree[id] = cmb(tree[id << 1], tree[id << 1 | 1]);
        }
    };
    auto get = [&](auto get, int u, int v, int id = 1, int l = 1, int r = m) {
        if (u <= l && r <= v) {
            return tree[id];
        }
        int mid = l + r >> 1;
        if (u <= mid && mid < v) {
            return cmb(get(get, u, v, id << 1, l, mid), get(get, u, v, id << 1 | 1, mid + 1, r));
        }
        if (u <= mid) {
            return get(get, u, v, id << 1, l, mid);
        }
        return get(get, u, v, id << 1 | 1, mid + 1, r);
    };
    for (int i = 1; i <= n; ++i) {
        int tr = upper_bound(R.begin(), R.end(), event[i].second) - R.begin();
        upd(tr, i);
    }
    for (int i = 1; i <= n; ++i) {
        int L = lower_bound(R.begin(), R.end(), event[i].first) - R.begin() + 1;
        int tr = upper_bound(R.begin(), R.end(), event[i].second) - R.begin();
        up[0][i] = get(get, L, tr);
    }
    for (int j = 1; j < LOG; ++j) {
        for (int i = 1; i <= n; ++i) {
            up[j][i] = up[j - 1][up[j - 1][i]];
        }
    }
    auto reach = [&](int u, int v) {
        if (v == -1) {
            return false;
        }
        return event[v].first <= event[u].second && event[u].second <= event[v].second;
    };
    auto qry = [&](int s, int t) {
        if (t == s) {
            cout << 0 << "\n";
            return;
        }
        if (event[s].second > event[t].second) {
            cout << "impossible\n";
            return;
        }
        if (event[t].first <= event[s].second) {
            cout << (reach(s, t) ? "1" : "impossible") << "\n";
            return;
        }
        int res = 0;
        for (int i = LOG - 1; i >= 0; --i) {
            int u = up[i][t];
            if (u != -1 && event[u].first > event[s].second) {
                t = u;
                res += MASK(i);
            }
        }
        t = up[0][t];
        if (reach(s, t)) {
            cout << res + 2 << "\n";
        } else {
            cout << "impossible\n";
        }
    };
    while (q--) {
        int s, t;
        cin >> s >> t;
        qry(s, t);
    }
}

Compilation message (stderr)

events.cpp: In lambda function:
events.cpp:49:25: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   49 |             int mid = l + r >> 1;
      |                       ~~^~~
events.cpp: In instantiation of 'main()::<lambda(auto:23, int, int, int, int, int)> [with auto:23 = main()::<lambda(auto:23, int, int, int, int, int)>]':
events.cpp:84:34:   required from here
events.cpp:68:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   68 |         int mid = l + r >> 1;
      |                   ~~^~~

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