제출 #540458

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
540458		elazarkoren	From Hacks to Snitches (BOI21_watchmen)	C++17	5 / 100	6035 ms	58444 KiB

watchmen

#include <bits/stdc++.h>
#define x first
#define y second
#define all(v) v.begin(), v.end()
#define chkmin(a, b) a = min(a, b)
#define chkmax(a, b) a = max(a, b)
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int, int> pii;
typedef vector<pii> vii;
typedef vector<bool> vb;

const int MAX_N = 1e5 + 5;
const int MAX_L = 5000;

int Gcd(int a, int b) {
    return (b ? Gcd(b, a % b) : a);
}

inline int Lcm(int a, int b) {
    return a * b / Gcd(a, b);
}

set<int> bad_node[MAX_L];
set<pii> bad_edge[MAX_L];
queue<pii> q[MAX_L];
bitset<MAX_N> visited[MAX_L];

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int n, m;
    cin >> n >> m;
    vvi graph(n + 1);
    for (int i = 0; i < m; i++) {
        int a, b;
        cin >> a >> b;
        graph[a].push_back(b);
        graph[b].push_back(a);
    }
    int k;
    cin >> k;
    vi len(k);
    vvi path(k);
    int l = 1;
    for (int j = 0; j < k; j++) {
        cin >> len[j];
        path[j].resize(len[j]);
        l = Lcm(len[j], l);
        for (int i = 0; i < len[j]; i++) {
            cin >> path[j][i];
        }
    }
    for (int j = 0; j < k; j++) {
//        path[j][l] = path[j][0];
        for (int i = 1; i <= l; i++) {
            bad_node[i].insert(path[j][i % len[j]]);
            bad_edge[i].insert({min(path[j][i % len[j]], path[j][(i - 1) % len[j]]), max(path[j][i % len[j]], path[j][(i - 1) % len[j]])});
        }
    }
    swap(bad_node[0], bad_node[l]);
    swap(bad_edge[0], bad_edge[l]);
    q[0].push({1, 0});
    for (int i = 0; ; i++) {
        if (i == l) i = 0;
        if (q[i].empty()) break;
        int t = (i + 1) % l;
        while (!q[i].empty()) {
            auto [node, d] = q[i].front();
            if (node == n) {
                cout << d << '\n';
                return 0;
            }
            q[i].pop();
            if (!visited[t][node] && !bad_node[t].count(node)) {
                visited[t][node] = true;
                q[t].push({node, d + 1});
            }
            for (int neighbor : graph[node]) {
                if (!visited[t][neighbor] && !bad_node[t].count(neighbor)) {
                    if (!bad_edge[t].count({min(node, neighbor), max(node, neighbor)})) {
                        visited[t][neighbor] = true;
                        q[t].push({neighbor, d + 1});
                    }
                }
            }
        }
    }
    cout << "impossible\n";
    return 0;
}
//6 6
//1 2
//2 3
//3 4
//4 5
//5 2
//5 6
//1
//4 3 2 5 4

• Subtask 1: 5 / 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