Submission #928853

#	Time	Username	Problem	Language	Result	Execution time	Memory
928853		math_rabbit_1028	Newspapers (CEOI21_newspapers)	C++14	8 / 100	1 ms	488 KiB

newspapers

#include <bits/stdc++.h>
using namespace std;

int N, M;
vector<int> adj[1010];
int ch[1010], par[1010], dia[1010];

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

    cin >> N >> M;
    for (int i = 1; i <= M; i++) {
        int a, b;
        cin >> a >> b;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }

    if (M >= N) {
        cout << "NO\n";
        return 0;
    }

    queue<int> q;
    int r, s;
    for (int i = 1; i <= N; i++) ch[i] = 0;
    q.push(1);
    while (!q.empty()) {
        int v = q.front();
        r = v;
        q.pop();
        ch[v] = 1;
        for (int u : adj[v]) {
            if (ch[u]) continue;
            q.push(u);
        }
    }
    
    par[r] = 0;
    for (int i = 1; i <= N; i++) ch[i] = 0;
    q.push(r);
    while (!q.empty()) {
        int v = q.front();
        s = v;
        q.pop();
        ch[v] = 1;
        for (int u : adj[v]) {
            if (ch[u]) continue;
            par[u] = v;
            q.push(u);
        }
    }
    // cout << r << " " << s << "\n";
    while (s > 0) {
        dia[s] = 1;
        s = par[s];
    }
    for (int i = 1; i <= N; i++) {
        if (dia[i]) continue;
        for (int v : adj[i]) {
            if (dia[v]) continue;
            cout << "NO\n";
            return 0;
        }
    }
    
    cout << "YES\n";
    if (N == 1) cout << "1\n1\n";
    else if (N == 2) cout << "2\n1 1\n";
    else {
        cout << 2*N-4 << "\n";
        for (int i = 2; i <= N-1; i++) cout << i << " ";
        for (int i = N-1; i >= 2; i--) cout << i << " ";
        cout << "\n";   
    }

    return 0;
}

Compilation message (stderr)

newspapers.cpp: In function 'int main()':
newspapers.cpp:57:11: warning: 's' may be used uninitialized in this function [-Wmaybe-uninitialized]
   57 |         s = par[s];
      |         ~~^~~~~~~~

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