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Submission #697799

# Submission time Handle Problem Language Result Execution time Memory
697799 2023-02-11T06:09:55 Z Duy_e Event Hopping (BOI22_events) C++14
25 / 100
 1500 ms 52256 KB 
#include <bits/stdc++.h>
#define ll long long
#define pii pair <ll, ll>
#define st first
#define nd second
#define rep(i, n, m) for (ll i = (n); i <= (m); i ++)
#define rrep(i, n, m) for (ll i = (n); i >= (m); i --)
using namespace std;

const long long INF = 1e18;
const long long N = 1e5 + 5;

ll n, q, s[N], e[N];
vector <int> cmp, out[2 * N], in[2 * N];
vector <int> d[N];

const ll Nmax = 5005;
int dist[Nmax][Nmax];
void bfs(int st, int *f) {
    rep(i, 1, n) f[i] = 1e9;
    f[st] = 0;
    queue <int> q;
    q.push(st);
    while (q.size()) {
        int u = q.front(); q.pop();
        for (int v: d[u]) if (f[v] > f[u] + 1) {
            f[v] = f[u] + 1;
            q.push(v);
        }
    }
}

namespace sub4 {

    pii a[N];
    ll pos[N], f[N];
    void solve() {
        rep(i, 1, n) a[i] = {e[i], i};
        sort(a + 1, a + 1 + n);
        rep(i, 1, n) pos[a[i].nd] = i;
        while (q --) {
            int u, v;
            cin >> u >> v;
            int i = pos[u];
            int j = pos[v];
            int l = j;

            if (i > j && a[j].st < a[i].st) {
                cout << "impossible\n";
                continue;
            }

            if (i > j) {
                cout << 1 << '\n';
                continue;
            }

            while (l + 1 <= n && a[l + 1].st == a[j].st) l ++;

            f[l + 1] = 1e9;
            //cout << i << ' ' << j << '\n';
            rrep(k, l, i) {
                int id = a[k].nd;
                f[k] = min(f[k + 1], s[id]);
            }
            int ans = 0;
            while (i < j) {
                ans ++;
                int cur = a[i].st, pre = i;
                while (i < l && cur >= f[i + 1]) {
                    i ++;
                }
                if (i > j) {
                    int id = a[j].nd;
                    if (cur >= s[v] && cur <= e[v])
                        break;
                    ans ++;
                    break;
                }
                if (i == pre) break;

            }

            //cout << i << ' ' << j << '\n';

            if (i >= j)
                cout << ans << '\n';
            else
                cout << "impossible\n";
        }
    }
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    cin >> n >> q;
    rep(i, 1, n) {
        cin >> s[i] >> e[i];
        cmp.push_back(s[i]);
        cmp.push_back(e[i]);
    }

    sort(cmp.begin(), cmp.end());
    cmp.resize(unique(cmp.begin(), cmp.end()) - cmp.begin());

    auto find = [&] (ll x) {
        return lower_bound(cmp.begin(), cmp.end(), x) - cmp.begin() + 1;
    };

    rep(i, 1, n) {
        s[i] = find(s[i]);
        e[i] = find(e[i]);
        in[s[i]].push_back(i);
        out[e[i]].push_back(i);
    }

    if (q <= 100) {
        sub4 :: solve();
        return 0;
    }

    set <int> save;
    rep(timer, 1, 2 * n) {
        for (int i: in[timer]) save.insert(i);
        for (int i: out[timer]) {
            for (int j: save)
                d[i].push_back(j);
        }

        for (int i: out[timer])
            save.erase(i);
    }

    rep(i, 1, n) bfs(i, dist[i]);

    while (q --) {
        int u, v;
        cin >> u >> v;
        if (dist[u][v] >= (int)1e9)
            cout << "impossible\n";
        else
            cout << dist[u][v] << '\n';
    }

    return 0;
}

Compilation message

events.cpp: In function 'void sub4::solve()':
events.cpp:74:25: warning: unused variable 'id' [-Wunused-variable]
   74 |                     int id = a[j].nd;
      |                         ^~

Subtask #1
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11988 KB Output is correct
2 Execution timed out 1592 ms 44236 KB Time limit exceeded
3 Halted 0 ms 0 KB -

Subtask #2
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11988 KB Output is correct
2 Correct 6 ms 11988 KB Output is correct
3 Correct 8 ms 12116 KB Output is correct
4 Correct 7 ms 12116 KB Output is correct
5 Correct 7 ms 12116 KB Output is correct
6 Correct 7 ms 12084 KB Output is correct
7 Correct 7 ms 12116 KB Output is correct
8 Correct 7 ms 12116 KB Output is correct
9 Correct 7 ms 12116 KB Output is correct

Subtask #3
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11988 KB Output is correct
2 Correct 6 ms 11988 KB Output is correct
3 Correct 8 ms 12116 KB Output is correct
4 Correct 7 ms 12116 KB Output is correct
5 Correct 7 ms 12116 KB Output is correct
6 Correct 7 ms 12084 KB Output is correct
7 Correct 7 ms 12116 KB Output is correct
8 Correct 7 ms 12116 KB Output is correct
9 Correct 7 ms 12116 KB Output is correct
10 Correct 7 ms 11988 KB Output is correct
11 Correct 7 ms 11988 KB Output is correct
12 Correct 7 ms 12116 KB Output is correct
13 Correct 7 ms 12176 KB Output is correct
14 Correct 7 ms 12116 KB Output is correct
15 Correct 7 ms 12116 KB Output is correct
16 Correct 7 ms 12116 KB Output is correct
17 Correct 7 ms 12116 KB Output is correct
18 Correct 6 ms 12116 KB Output is correct
19 Execution timed out 1578 ms 52256 KB Time limit exceeded
20 Halted 0 ms 0 KB -

Subtask #4
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11988 KB Output is correct
2 Correct 6 ms 11988 KB Output is correct
3 Correct 8 ms 12116 KB Output is correct
4 Correct 7 ms 12116 KB Output is correct
5 Correct 7 ms 12116 KB Output is correct
6 Correct 7 ms 12084 KB Output is correct
7 Correct 7 ms 12116 KB Output is correct
8 Correct 7 ms 12116 KB Output is correct
9 Correct 7 ms 12116 KB Output is correct
10 Correct 7 ms 11988 KB Output is correct
11 Correct 6 ms 11988 KB Output is correct
12 Correct 8 ms 12116 KB Output is correct
13 Correct 7 ms 12116 KB Output is correct
14 Correct 7 ms 12212 KB Output is correct
15 Correct 7 ms 12116 KB Output is correct
16 Correct 8 ms 12116 KB Output is correct
17 Correct 7 ms 12116 KB Output is correct
18 Correct 6 ms 12116 KB Output is correct
19 Correct 163 ms 23760 KB Output is correct
20 Correct 99 ms 23768 KB Output is correct
21 Correct 98 ms 20752 KB Output is correct
22 Correct 105 ms 23712 KB Output is correct
23 Correct 102 ms 23764 KB Output is correct
24 Correct 141 ms 23724 KB Output is correct
25 Correct 70 ms 18632 KB Output is correct

Subtask #5
0 / 20.0

# Verdict Execution time Memory Grader output
1 Execution timed out 1592 ms 43948 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #6
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11988 KB Output is correct
2 Execution timed out 1592 ms 44236 KB Time limit exceeded
3 Halted 0 ms 0 KB -