Submission #649825

#	Time	Username	Problem	Language	Result	Execution time	Memory
649825		1bin	Newspapers (CEOI21_newspapers)	C++14	100 / 100	77 ms	8208 KiB

newspapers

#include <bits/stdc++.h>

using namespace std;

#define all(v) v.begin(), v.end()
typedef long long ll;
const int NMAX = 1e3 + 5;
int n, m, a, b, ix, mxd, er;
vector<int> adj[NMAX], ans;

void go(int x, int p, int d){
    if(d > mxd){
        mxd = d; ix= x;
    }
    for(int& nx : adj[x]){
        if(nx == p) continue;
        go(nx, x, d + 1);
    }
    return;
}

int dfs(int x, int p){
    if(x == b) return 1;
    int t = -1;
    for(int& nx : adj[x]){
        if(nx == p) continue;
        if(dfs(nx, x)) {
            t = nx; break;
        }
    }
    if(t != -1){
        ans.emplace_back(x);
        for(int& nx : adj[x]){
            if(nx == p) continue;
            if(nx != t){
                mxd = 0; go(nx, x, 1);
                if(mxd >= 3) er = 1;
                else if(mxd == 2) {
                    ans.emplace_back(nx);
                    ans.emplace_back(x);
                }
            }
        }
    }
    return t != -1;
}

int solve(){
    if(n <= 2) {
        while(n--) ans.emplace_back(1);
        return 1;
    }
    mxd = -1; go(1, -1, 0); b = ix;
    mxd = -1; go(b, -1, 1); a = ix;
    dfs(adj[a][0], a);
    for(int i = ans.size() - 1; i >= 0; i--) ans.emplace_back(ans[i]);
    return !er;
}

int main(void){
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    
    cin >> n >> m;
    for(int i = 0; i < m; i++){
        cin >> a >> b;
        adj[a].emplace_back(b);
        adj[b].emplace_back(a);
    }    
    if(m == n - 1 && solve()) {
        cout << "YES\n";
        cout << ans.size() << '\n';
        for(int& x : ans) cout << x << ' ';
    }
    else cout << "NO";
    return 0;
}

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