oj.uz

Submission #721899

# Submission time Handle Problem Language Result Execution time Memory
721899 2023-04-11T08:37:08 Z The_Samurai Event Hopping (BOI22_events) C++17
10 / 100
 1319 ms 8348 KB 
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2")

#include "bits/stdc++.h"

using namespace std;
using ll = long long;
int INF = 2e9;

struct node {
    int l, r, i;
};

bool comp(node a, node b) {
    if (a.r < b.r) return true;
    if (a.r > b.r) return false;
    return a.l < b.l;
}

void solve() {
    int n, q;
    cin >> n >> q;
    vector<node> a(n);
    for (int i = 0; i < n; i++) {
        cin >> a[i].l >> a[i].r;
        a[i].i = i + 1;
    }
    sort(a.begin(), a.end(), comp);
    if (n <= 1000) {
        vector<int> ind(n + 1);
        for (int i = 0; i < n; i++) {
            ind[a[i].i] = i;
        }
        vector<vector<int>> can(n + 1, vector<int>(n + 1, -1));
        vector<vector<int>> g(n + 1);
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                if (a[j].l <= a[i].r and a[i].r <= a[j].r) {
                    g[i].emplace_back(j);
                }
            }
        }
        for (int i = 0; i < n; i++) {
            can[i][i] = 0;
            queue<int> pq;
            pq.push(i);
            while (!pq.empty()) {
                int u = pq.front();
                pq.pop();
                for (int v: g[u]) {
                    if (can[i][v] == -1) {
                        can[i][v] = can[i][u] + 1;
                        pq.push(v);
                    }
                }
            }
        }
        while (q--) {
            int si, ei;
            cin >> si >> ei;
            si = ind[si];
            ei = ind[ei];
            if (can[si][ei] == -1) cout << "impossible";
            else cout << can[si][ei];
            cout << '\n';
        }
        return;
    }
    vector<int> id(n + 1);
    for (int i = 0; i < n; i++)
        id[a[i].i] = i;
    vector<pair<int, int>> ind(n, {-1, -1});
    int cnt = 0;
    auto get = [&](int u) {
        for (int i = max(u - 2, 0); i < min(n, u + 2); i++) {
            if (i == u) continue;
            if (a[i].l <= a[u].r and a[u].r <= a[i].r) return i;
        }
        return -1;
    };
    for (int i = 0; i < n; i++) {
        if (ind[i].first != -1) continue;
        ind[i] = {cnt, 0};
        int j = i, k = get(i);
        int now = 1;
        set<int> way = {-1, i};
        while (!way.count(k)) {
            way.insert(j);
            j = k;
            k = get(j);
            ind[j] = {cnt, now};
            now++;
        }
    }
    while (q--) {
        int si, ei;
        cin >> si >> ei;
        si = id[si];
        ei = id[ei];
        if (get(si) == ei) {
            cout << "1\n";
        } else if (si == ei) {
            cout << "0\n";
        } else if (ind[si].first == ind[ei].first and ind[si].second < ind[ei].second) {
            cout << ind[ei].second - ind[si].second + 1 << '\n';
        } else {
            cout << "impossible\n";
        }
    }
}

int main() {
    ios_base::sync_with_stdio(false);
    cout.tie(nullptr);
    cin.tie(nullptr);

    int queries = 1;
#ifdef test_cases
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
//    cin >> queries;
#else
    //    cin >> queries;
#endif

    for (int test_case = 1; test_case <= queries; test_case++) {
        solve();
//        cout << '\n';
    }
}

Subtask #1
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Incorrect 118 ms 8016 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #2
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 9 ms 4308 KB Output is correct
4 Correct 7 ms 4316 KB Output is correct
5 Correct 10 ms 4352 KB Output is correct
6 Correct 57 ms 5136 KB Output is correct
7 Correct 168 ms 5936 KB Output is correct
8 Correct 232 ms 6976 KB Output is correct
9 Correct 1122 ms 8340 KB Output is correct

Subtask #3
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 9 ms 4308 KB Output is correct
4 Correct 7 ms 4316 KB Output is correct
5 Correct 10 ms 4352 KB Output is correct
6 Correct 57 ms 5136 KB Output is correct
7 Correct 168 ms 5936 KB Output is correct
8 Correct 232 ms 6976 KB Output is correct
9 Correct 1122 ms 8340 KB Output is correct
10 Correct 1 ms 212 KB Output is correct
11 Correct 1 ms 212 KB Output is correct
12 Correct 10 ms 4308 KB Output is correct
13 Correct 7 ms 4308 KB Output is correct
14 Correct 10 ms 4308 KB Output is correct
15 Correct 54 ms 5136 KB Output is correct
16 Correct 160 ms 5944 KB Output is correct
17 Correct 251 ms 6996 KB Output is correct
18 Correct 1151 ms 8344 KB Output is correct
19 Incorrect 32 ms 1552 KB Output isn't correct
20 Halted 0 ms 0 KB -

Subtask #4
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 9 ms 4308 KB Output is correct
4 Correct 7 ms 4316 KB Output is correct
5 Correct 10 ms 4352 KB Output is correct
6 Correct 57 ms 5136 KB Output is correct
7 Correct 168 ms 5936 KB Output is correct
8 Correct 232 ms 6976 KB Output is correct
9 Correct 1122 ms 8340 KB Output is correct
10 Correct 1 ms 320 KB Output is correct
11 Correct 0 ms 320 KB Output is correct
12 Correct 10 ms 4372 KB Output is correct
13 Correct 8 ms 4308 KB Output is correct
14 Correct 10 ms 4360 KB Output is correct
15 Correct 58 ms 5076 KB Output is correct
16 Correct 161 ms 5944 KB Output is correct
17 Correct 205 ms 6992 KB Output is correct
18 Correct 1319 ms 8348 KB Output is correct
19 Incorrect 65 ms 7908 KB Output isn't correct
20 Halted 0 ms 0 KB -

Subtask #5
0 / 20.0

# Verdict Execution time Memory Grader output
1 Incorrect 95 ms 8016 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #6
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Incorrect 118 ms 8016 KB Output isn't correct
3 Halted 0 ms 0 KB -