Submission #479150

#	Time	Username	Problem	Language	Result	Execution time	Memory
479150		errorgorn	Newspapers (CEOI21_newspapers)	C++17	100 / 100	99 ms	23876 KiB

newspapers

//雪花飄飄北風嘯嘯
//天地一片蒼茫

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define ll long long
#define ii pair<ll,ll>
#define iii pair<ii,ll>
#define fi first
#define se second
#define endl '\n'
#define debug(x) cout << #x << ": " << x << endl

#define pub push_back
#define pob pop_back
#define puf push_front
#define pof pop_front
#define lb lower_bound
#define ub upper_bound

#define rep(x,start,end) for(auto x=(start)-((start)>(end));x!=(end)-((start)>(end));((start)<(end)?x++:x--))
#define all(x) (x).begin(),(x).end()
#define sz(x) (int)(x).size()

#define indexed_set tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>
//change less to less_equal for non distinct pbds, but erase will bug

mt19937 rng(chrono::system_clock::now().time_since_epoch().count());

const int MOD=998244353;

ll qexp(ll b,ll p,int m){
    ll res=1;
    while (p){
        if (p&1) res=(res*b)%m;
        b=(b*b)%m;
        p>>=1;
    }
    return res;
}

ll inv(ll i){
	return qexp(i,MOD-2,MOD);
}

ll fix(ll i){
	i%=MOD;
	if (i<0) i+=MOD;
	return i;
}

ll fac[1000005];
ll ifac[1000005];

ll nCk(int i,int j){
	if (i<j) return 0;
	return fac[i]*ifac[j]%MOD*ifac[i-j]%MOD;
}

int n,m;
vector<int> al[1005];
vector<int> al2[1005];

bool path[1005];
bool vis[1005];

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin.exceptions(ios::badbit | ios::failbit);
	
	fac[0]=1;
	rep(x,1,1000005) fac[x]=fac[x-1]*x%MOD;
	ifac[1000004]=inv(fac[1000004]);
	rep(x,1000005,1) ifac[x-1]=ifac[x]*x%MOD;
	
	cin>>n>>m;
	
	int a,b;
	rep(x,0,m){
		cin>>a>>b;
		a--,b--;
		
		al[a].pub(b);
		al[b].pub(a);
	}
	
	if (n==1){
		cout<<"YES"<<endl;
		cout<<1<<endl;
		cout<<1<<endl;
	}
	else if (n==2){
		cout<<"YES"<<endl;
		cout<<2<<endl;
		cout<<2<<" "<<2<<endl;
	}
	else{
		if (n==m+1){
			rep(x,0,n) if (sz(al[x])!=1) path[x]=true;
			
			rep(x,0,n) for (auto &it:al[x]){
				if (path[x] && path[it]) al2[x].pub(it);
			}
			
			rep(x,0,n) swap(al[x],al2[x]);
			
			rep(x,0,n) if (path[x] && sz(al[x])<=1){
				memset(vis,false,sizeof(vis));
				int curr=x;
				vector<int> ans={x};
				vis[x]=true;
				bool can=true;
				
				if (sz(al[x])) while (true){
					int cnt=0;
					for (auto &it:al[curr]) if (!vis[it]){
						if (sz(al[it])>1) cnt++;
					}
					
					if (cnt>1){
						can=false;
						break;
					}
					if (cnt==0){
						for (auto &it:al[curr]) if (!vis[it]){
							vis[it]=true;
							ans.pub(it);
							ans.pub(curr);
						}
						ans.pob();
						break;
					}
					else{
						for (auto &it:al[curr]) if (!vis[it] && sz(al[it])==1){
							vis[it]=true;
							ans.pub(it);
							ans.pub(curr);
						}
						for (auto &it:al[curr]) if (!vis[it]){
							vis[it]=true;
							ans.pub(it);
							curr=it;
							break;
						}
					}
				}
				
				if (can){
					cout<<"YES"<<endl;
					cout<<sz(ans)*2<<endl;
					for (auto it:ans) cout<<it+1<<" "; 
					reverse(all(ans));
					for (auto it:ans) cout<<it+1<<" "; cout<<endl;
					return 0;
				}
			}
			cout<<"NO"<<endl;
		}
		else{
			cout<<"NO"<<endl;
		}
	}
}

Compilation message (stderr)

newspapers.cpp: In function 'int main()':
newspapers.cpp:160:6: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  160 |      for (auto it:ans) cout<<it+1<<" "; cout<<endl;
      |      ^~~
newspapers.cpp:160:41: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
  160 |      for (auto it:ans) cout<<it+1<<" "; cout<<endl;
      |                                         ^~~~

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