Submission #593981

#	Time	Username	Problem	Language	Result	Execution time	Memory
593981		vladislav11	Newspapers (CEOI21_newspapers)	C++14	20 / 100	2 ms	2772 KiB

newspapers

#include <bits/stdc++.h>

using namespace std;

int n, m;
vector< vector<int> > grp;
vector<int> used;

void dfs ( int v, int p )
{
    used[v] = 1;

    for ( auto& to : grp[v] )
    if ( to != p )
    {
        if ( used[to] )
        {
            cout << "NO\n";
            exit(0);
        }

        dfs( to, v );
    }
}

const int N = 1<<20;
pair<int,int> pre[N];

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

    cin >> n >> m;

    grp.resize( n+1 );

    for ( int i=0; i<m; i++ )
    {
        int u, v;
        cin >> u >> v;

        grp[u].push_back( v );
        grp[v].push_back( u );
    }

    used.assign( n+1, 0 );

    dfs( 1, -1 );

    if ( n <= 20 )
    {
        queue<int> q;
        q.push( (1<<n)-1 );

        while ( q.size() && pre[0].second == 0 )
        {
            int v = q.front();
            q.pop();

            int x = 0;

            for ( int i=0; i<n; i++ )
            if ( (v>>i) & 1 )
            for ( auto& to : grp[i+1] )
                x |= 1 << (to-1);

            for ( int i=0; i<n; i++ )
            if ( pre[ x & (~(1<<i)) ].second == 0 )
            {
                pre[ x & (~(1<<i)) ] = { v, i+1 };
                q.push( x & (~(1<<i)) );

                if ( ( x & (~(1<<i)) ) == 0 )
                    break;
            }
        }

        if ( pre[0].second == 0 )
        {
            cout << "NO\n";
            return 0;
        }

        vector<int> ans;

        int pos = 0;

        while ( pos != (1<<n)-1 )
        {
            ans.push_back( pre[pos].second );
            pos = pre[pos].first;
        }

        cout << "YES\n";

        cout << ans.size() << '\n';

        while ( ans.size() )
        {
            cout << ans.back() << ' ';
            ans.pop_back();
        }

        return 0;
    }

    cout << "YES\n";

    if ( n == 1 )
    {
        cout << "1 1";
        return 0;
    }

    if ( n == 2 )
    {
        cout << "2 1 1";
        return 0;
    }

    cout << 2*(n-2) << '\n';

    for ( int i=2; i<n; i++ )
        cout << i << ' ';

    for ( int i=n-1; i>1; i-- )
        cout << i << ' ';

    return 0;
}

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