제출 #520446

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
520446		KoD	Newspapers (CEOI21_newspapers)	C++17	0 / 100	1 ms	460 KiB

newspapers

#include <bits/stdc++.h>

using std::vector;
using std::array;
using std::pair;
using std::tuple;

vector<int> naive(const vector<vector<int>>& graph) {
    const int N = graph.size();
    vector<int> adj(1 << N);
    for (int set = 0; set < (1 << N); ++set) {
        for (int i = 0; i < N; ++i) {
            if (set >> i & 1) {
                for (const int j : graph[i]) {
                    adj[set] |= 1 << j;
                }
            }
        }
    }
    vector<vector<pair<int, int>>> transit(1 << N);
    for (int set = 0; set < (1 << N); ++set) {
        for (int i = 0; i < N; ++i) {
            transit[adj[set] & ~(1 << i)].emplace_back(set, i);
        }
    }
    vector<int> dist(1 << N, -1), last(1 << N, -1);
    std::queue<int> que;
    const auto push = [&](const int u, const int d, const int l) {
        if (dist[u] == -1) {
            dist[u] = d;
            last[u] = l;
            que.push(u);
        }
    };
    push(0, 0, -1);
    while (!que.empty()) {
        const int u = que.front();
        que.pop();
        for (const auto& [v, i] : transit[u]) {
            push(v, dist[u] + 1, i);
        }
    }
    int set = (1 << N) - 1;
    if (dist[set] == -1) {
        return {};
    }
    vector<int> ans;
    while (set != 0) {
        ans.push_back(last[set] + 1);
        set = adj[set] & ~(1 << last[set]);
    }
}

int main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(nullptr);
    int N, M;
    std::cin >> N >> M;
    if (M != N - 1) {
        std::cout << "NO\n";
        return 0;
    }
    vector<vector<int>> graph(N);
    for (int i = 0; i < M; ++i) {
        int a, b;
        std::cin >> a >> b;
        a -= 1, b -= 1;
        graph[a].push_back(b);
        graph[b].push_back(a);
    }
    if (N <= 20) {
        const auto ans = naive(graph);
        const int n = ans.size();
        std::cout << "YES\n" << n << '\n';
        for (int i = 0; i < n; ++i) {
            std::cout << ans[i] << " \n"[i + 1 == n];
        }
    } else {
        std::cout << "YES\n";
        if (N % 2 == 0) {
            std::cout << 2 * (N - 2) << '\n';
            for (int i = 2; i < N; ++i) {
                std::cout << i << ' ';
            }
            for (int i = N - 1; i >= 2; --i) {
                std::cout << i << " \n"[i == 2];
            }
        } else {
            std::cout << 2 * (N - 2) << '\n';
            for (int i = 2; i < N; ++i) {
                std::cout << i << ' ';
            }
            for (int i = 2; i < N; ++i) {
                std::cout << i << " \n"[i == N - 1];
            }
        }
    }
    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

newspapers.cpp: In function 'std::vector<int> naive(const std::vector<std::vector<int> >&)':
newspapers.cpp:10:27: warning: control reaches end of non-void function [-Wreturn-type]
   10 |     vector<int> adj(1 << N);
      |                           ^

• Subtask 1: 0 / 12
• Subtask 2: 0 / 8
• Subtask 3: 0 / 80