Submission #1003835

#	Time	Username	Problem	Language	Result	Execution time	Memory
1003835		vjudge1	Pastiri (COI20_pastiri)	C++17	8 / 100	211 ms	72472 KiB

pastiri

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

#define fi first
#define se second
#define pb push_back
#define all(x) x.begin(), x.end()
#define allr(x) x.rbegin(), x.rend()
#define mp make_pair

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef complex<double> cd;

const int MAXN = 5e5+10;
const int MOD = 1e9+7;
const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3f;
const double PI = acos(-1);

vector<int> adj[MAXN];
int prof[MAXN], dist[MAXN], elim[MAXN], pai[MAXN];

void build(int ver, int prev=0){
	prof[ver]=prof[prev]+1;
	pai[ver]=prev;
	
	for(auto u : adj[ver]){
		if(u==prev) continue;
		build(u, ver);
	}
}

void dfs(int ver, int val, int lim){
	elim[ver]=1;
	if(val==lim) return;
	
	for(auto u : adj[ver]){
		if(elim[u]) continue;
		dfs(u, val+1, lim);
	}
}

void solve(){
	int n, k; cin >> n >> k;
	
	for(int i=0;i<n-1;i++){
		int a, b; cin >> a >> b;
		adj[a].pb(b);
		adj[b].pb(a);
	}
	
	for(int i=1;i<=n;i++)
		dist[i]=-1;
	
	vector<int> spec(k);
	queue<int> q;
	for(int i=0;i<k;i++){
		cin >> spec[i];
		q.push(spec[i]);
		dist[spec[i]]=0;
	}
	
	while(!q.empty()){
		int curr=q.front();
		q.pop();
		
		for(auto u : adj[curr]){
			if(dist[u]==-1){
				dist[u]=dist[curr]+1;
				q.push(u);
			}
		}
	}
	
	build(1);
	sort(all(spec), [&](int a, int b){ return prof[a]>prof[b]; });
	
	vector<int> ans;
	for(auto u : spec){
		if(elim[u]) continue;
		
		int at=u, d=0;
		while(pai[at]!=0 && dist[pai[at]]==d+1 && !elim[pai[at]]){
			d++;
			at=pai[at];
		}
		
		ans.pb(at);
		dfs(at, 0, d);
	}
	
	cout << (int)ans.size() << "\n";
	for(int i=0;i<(int)ans.size();i++) cout << ans[i] << " \n"[i==(int)ans.size()-1];
}

int32_t main(){
	ios_base::sync_with_stdio(false); cin.tie(NULL);
	
	int tt=1;
	//~ cin >> tt;
	while(tt--) solve();
	return 0;
}

• Subtask 1: 8 / 8
• Subtask 2: 0 / 18
• Subtask 3: 0 / 23
• Subtask 4: 0 / 51