제출 #1067399

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1067399		Andrey	Newspapers (CEOI21_newspapers)	C++14	0 / 100	1 ms	600 KiB

newspapers

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

vector<int> haha[10000];
vector<int> wow(0);
vector<int> wut(0);
int n,m;

void dfs(int a, int t, int d) {
    if(d%2) {
        wow.push_back(a);
    }
    else {
        wut.push_back(a);
    }
    for(int v: haha[a]) {
        if(v != t) {
            dfs(v,a,d+1);
        }
    }
}

bool check() {
    vector<int> br(n+1);
    vector<int> br1(n+1);
    for(int i = 1; i <= n; i++) {
        br[i] = haha[i].size();
    }
    for(int a: wow) {
        if(haha[a].size() == 1) {
            br[haha[a][0]]--;
            br[a] = -1;
        }
    }
    for(int i = 1; i <= n; i++) {
        br1[i] = br[i];
    }
    for(int i = 1; i <= n; i++) {
        if(br1[i] == 1) {
            for(int v: haha[i]) {
                br[v]--;
            }
            br[i] = -1;
        }
    }
    for(int i = 1; i <= n; i++) {
        if(br[i] > 2) {
            return false;
        }
    }
    return true;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    cin >> n >> m;
    int a,b;
    for(int i = 0; i < m; i++) {
        cin >> a >> b;
        haha[a].push_back(b);
        haha[b].push_back(a);
    }
    if(m > n-1) {
        cout << "NO" << endl;
        return 0;
    }
    dfs(1,-1,0);
    if(check()) {
        cout << "YES" << endl;
    }
    else {
        swap(wow,wut);
        if(check()) {
            cout << "YES" << endl;
        }
        else {
            cout << "NO" << endl;
        }
    }
    return 0;
}

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