Submission #1307360

#	Time	Username	Problem	Language	Result	Execution time	Memory
1307360		pvpro	From Hacks to Snitches (BOI21_watchmen)	C++20	0 / 100	6093 ms	19544 KiB

watchmen

#ifndef LOCAL
#pragma GCC Optimize("O3,Ofast,unroll-loops")
#pragma GCC Target("bmi,bmi2,avx,avx2")
#endif
#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using ld = long double;

#define int ll

#define f first 
#define s second 
#define mp make_pair 
#define pb push_back
#define pii pair<int, int>
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin() (x).rend()
#ifndef LOCAL
#define endl "\n"
#endif

mt19937 rnd(11);

void solve() {
    int n, m;
    cin >> n >> m;
    vector<vector<int>> graph(n);
    for (int i = 0; i < m; ++i) {
        int a, b;
        cin >> a >> b;
        --a; --b;
        graph[a].pb(b);
        graph[b].pb(a);
    }
    int k;
    cin >> k;
    vector<pii> bad(n, mp(0, 0));
    map<pii, pii> badE;
    for (int i = 0; i < k; ++i) {
        int sz;
        cin >> sz;
        vector<int> v(sz);
        for (auto &x : v) {
            cin >> x;
            --x;
        }
        for (int j = 0; j < sz; ++j) {
            bad[v[j]] = mp(sz, j);
            badE[mp(v[j], v[(j + 1) % v.size()])] = mp(sz, j);
            badE[mp(v[(j + 1) % v.size()], v[j])] = mp(sz, j);
        }
    }
    int T = n * 4;
    vector<vector<int>> d(n, vector<int>(T));
    d[0].assign(T, 1);
    for (int t = 0; t < T - 1; ++t) {
        for (int i = 0; i < n; ++i) {
            if (d[i][t]) {
                for (auto &u : graph[i]) {
                    if ((bad[u].f == 0 || ((t + 1) % bad[u].f != bad[u].s)) && (badE[mp(i, u)].f == 0 || (t % badE[mp(i, u)].f != badE[mp(i, u)].s))) {
                        d[u][t + 1] = 1;
                    }
                }
            }
        }
    }
    for (int i = 0; i < T; ++i) {
        if (d.back()[i]) {
            cout << i << endl;
            return;
        }
    }
    cout << "impossible" << endl;
}

signed main() {
    #ifdef LOCAL
        freopen("in.txt", "r", stdin);
        freopen("out.txt", "w", stdout);
    #else
        ios::sync_with_stdio(false);
        cin.tie(0);
    #endif
    int t = 1;
    // cin >> t;
    while (t--) {
        solve();
    }
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 10
• Subtask 5: 0 / 25
• Subtask 6: 0 / 20
• Subtask 7: 0 / 20