Submission #576484

#	Time	Username	Problem	Language	Result	Execution time	Memory
576484		talant117408	Newspapers (CEOI21_newspapers)	C++17	0 / 100	0 ms	212 KiB

newspapers

#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;

#define long                unsigned long 
#define pb                  push_back
#define mp                  make_pair
#define all(v)              (v).begin(),(v).end()
#define rall(v)             (v).rbegin(),(v).rend()
#define lb                  lower_bound
#define ub                  upper_bound
#define sz(v)               int((v).size())
#define do_not_disturb      ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define endl                '\n'

void solve() {
    int n, m;
    cin >> n >> m;
    vector <vector <int>> graph(n+1);
    vector <int> used(n+1), color(n+1, -1);
    for (int i = 1; i <= m; i++) {
        int a, b;
        cin >> a >> b;
        graph[a].pb(b);
        graph[b].pb(a);
    }
    int flag = 0;
    function<void(int, int, int)> dfs = [&](int v, int p, int c) {
        used[v] = 1;
        if (color[v] == -1) color[v] = c;
        for (auto to : graph[v]) {
            if (used[to]) {
                if (used[to] == 1 && to != p) {
                    flag = 1;
                }
                continue;
            }
            dfs(to, v, 1-c);
        }
        used[v] = 2;
    };
    dfs(1, 1, 1);
    if (flag) {
        cout << "NO" << endl;
        return;
    }
    int forbidden, start, forbidden_leaves = 0;
    for (int i = 1; i <= n; i++) {
        if (sz(graph[i]) == 1) {
            start = graph[i][0];
            forbidden = color[i];
            break;
        }
    }
    for (int i = 1; i <= n; i++) {
        if (sz(graph[i]) == 1 && forbidden == color[i]) {
            forbidden_leaves++;
        }
    }
    set <int> visited;
    vector <int> order;
    int add = 1;
    function <void(int, int)> dfs2 = [&](int v, int p) {
        if (add) {
            visited.insert(v);
            order.pb(v);
        }
        if (sz(visited) == n-forbidden_leaves) {
            add = 0;
        }
        for (auto to : graph[v]) {
            if (to == p) continue;
            if (sz(graph[to]) == 1 && color[to] == forbidden) continue;
            dfs2(to, v);
            if (add) {
                visited.insert(v);
                order.pb(v);
            }
        }
    };
    dfs2(start, start);
    cout << "YES" << endl;
    cout << sz(order)*2 << endl;
    for (auto to : order) cout << to << ' ';
    for (auto to : order) cout << to << ' ';
}

int main() {
    do_not_disturb
    
    int t = 1;
    //~ cin >> t;
    while (t--) {
        solve();
    }
    
    return 0;
}

Compilation message (stderr)

newspapers.cpp: In function 'void solve()':
newspapers.cpp:51:20: warning: 'start' may be used uninitialized in this function [-Wmaybe-uninitialized]
   51 |     int forbidden, start, forbidden_leaves = 0;
      |                    ^~~~~

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