Submission #858826

#	Time	Username	Problem	Language	Result	Execution time	Memory
858826		danikoynov	Newspapers (CEOI21_newspapers)	C++14	6 / 100	9 ms	600 KiB

newspapers

/**
 ____ ____ ____ ____ ____ ____
||l |||e |||i |||n |||a |||d ||
||__|||__|||__|||__|||__|||__||
|/__\|/__\|/__\|/__\|/__\|/__\|

**/

#include<bits/stdc++.h>
#define endl '\n'

using namespace std;
typedef long long ll;

void speed()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
}

const int maxn = 1010;
int n, m;
vector < int > adj[maxn];

int used[maxn], rev[maxn];
void bfs(int v)
{
    for (int i = 1; i <= n; i ++)
        used[i] = -1;
    used[v] = 0;
    rev[v] = 0;
    queue < int > q;
    q.push(v);
    while(!q.empty())
    {
        int cur = q.front();
        q.pop();
        for (int u : adj[cur])
        {
            if (used[u] == -1)
            {
                used[u] = used[cur] + 1;
                rev[u] = cur;
                q.push(u);
            }
        }
    }
}

vector < pair < int, int > > acc[maxn];

    vector < int > seq;
vector < int > act;

int mark[maxn];
void add_to_seq(int ver)
{
    seq.push_back(ver);
    int i = 0;
    while(i < act.size() && act[i] != ver)
        i ++;
    if (i != act.size())
        act.erase(act.begin() + i);

    for (int i = 1; i <= n; i ++)
    {
        mark[i] = 0;
    }
    vector < int > new_act;
    for (int v : act)
    {
        for (int u : adj[v])
            mark[u] = 1;
    }


    for (int i = 1; i <= n; i ++)
        if (mark[i])
        new_act.push_back(i);

    act = new_act;
}
void solve()
{
    cin >> n >> m;
    if (m != n - 1)
    {
        cout << "NO" << endl;
        return;
    }
    for (int i = 1; i <= m; i ++)
    {
        int v, u;
        cin >> v >> u;
        adj[v].push_back(u);
        adj[u].push_back(v);
    }

    if (n == 1)
    {
        cout << "YES" << endl << 1 << endl << 1 << endl;
        return;
    }

    if (n == 2)
    {
        cout << "YES" << endl << 2 << endl << "1 1" << endl;
        return;
    }

    bfs(1);
    int s = 1;
    for (int i = 1; i <= n; i ++)
        if (used[i] > used[s])
        s = i;

    bfs(s);
    int t = 1;
    for (int i = 1; i <= n; i ++)
        if (used[i] > used[t])
            t = i;
        /**for (int i = 1; i <= n; i ++)
            cout << used[i] << " ";
        cout << endl;*/

    vector < int > chain;
    int ver = t;
    while(ver != s)
    {
        chain.push_back(ver);
        ver = rev[ver];
    }
    chain.push_back(ver);
    reverse(chain.begin(), chain.end());

    /**cout << "-----------" << endl;
    for (int cur : chain)
        cout << cur << " ";
    cout << endl;*/
    for (int i = 1; i <= n; i ++)
    {
        used[i] = 0;
    }

    chain.erase(chain.begin());
    chain.pop_back();

    s = chain[0];
    t = chain.back();
    for (int cur : chain)
    {
        used[cur] = 1;
    }

    for (int cur : chain)
    {
        for (int nb : adj[cur])
        {
            if (used[nb])
                continue;
            for (int u : adj[nb])
            {
                if (u != cur)
                {
                    acc[cur].push_back({nb, u});
                }
            }
        }
    }


    for (int i = 1; i <= n; i ++)
    act.push_back(i);

    for (int cur : chain)
    {
        add_to_seq(cur);
        for (pair < int, int > d : acc[cur])
        {
                   add_to_seq(d.first);
                   add_to_seq(cur);
        }
    }


    int cnt = 0;
    while(act.size() > 0)
    {
        cnt ++;
        assert(cnt < 10 * n);
        int ver = act.back();
        add_to_seq(ver);
    }

    cout << "YES" << endl;
    cout << seq.size() << endl;
    for (int cur : seq)
        cout << cur << " ";
    cout << endl;



}

int main()
{
    solve();
    return 0;
}

Compilation message (stderr)

newspapers.cpp: In function 'void add_to_seq(int)':
newspapers.cpp:61:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   61 |     while(i < act.size() && act[i] != ver)
      |           ~~^~~~~~~~~~~~
newspapers.cpp:63:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   63 |     if (i != act.size())
      |         ~~^~~~~~~~~~~~~

• Subtask 1: 0 / 12
• Subtask 2: 6 / 8
• Subtask 3: 0 / 80