Submission #768594

#	Time	Username	Problem	Language	Result	Execution time	Memory
768594		flappybird	Pastiri (COI20_pastiri)	C++17	0 / 100	395 ms	53452 KiB

pastiri

#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx,avx2,fma")
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
#define MAX 500101
#define MAXS 20
#define INF 1000000000000000001
#define bb ' '
#define ln '\n'
#define Ln '\n'
vector<int> adj[MAX];
int dis[MAX];
int sheep[MAX];
vector<int> v;
int vis[MAX];
int dep[MAX];
int prt[MAX];
void dfs(int x, int p = 0) {
	prt[x] = p;
	for (auto v : adj[x]) {
		if (v == p) continue;
		dep[v] = dep[x] + 1;
		dfs(v, x);
	}
}
void down(int x, int p = 0) {
	for (auto v : adj[x]) if (v != p) {
		dis[v] = min(dis[v], dis[x] + 1);
		down(v, x);
	}
}
void chk(int x, int d, int p = 0) {
	sheep[x] = 0;
	if (!d) return;
	for (auto v : adj[x]) if (v != p) chk(v, d - 1, x);
}
signed main() {
	ios::sync_with_stdio(false), cin.tie(0);
	int N, K;
	cin >> N >> K;
	int i, a, b;
	for (i = 1; i < N; i++) {
		cin >> a >> b;
		adj[a].push_back(b);
		adj[b].push_back(a);
	}
	vector<int> sv;
	for (i = 1; i <= K; i++) {
		cin >> a;
		sv.push_back(a);
		sheep[a] = 1;
	}
	dfs(1);
	down(1);
	sort(sv.begin(), sv.end(), [&](int a, int b) {return dep[a] > dep[b]; });
	int cnt = 0;
	vector<int> ans;
	for (i = 1; i <= N; i++) vis[i] = 0;
	for (auto x : sv) {
		if (!sheep[x]) continue;
		cnt++;
		int v = x;
		while (1) {
			int p = prt[v];
			if (!p) break;
			if (dis[p] < dep[x] - dep[p]) break;
			v = p;
			//if (vis[v]) break;
		}
		ans.push_back(v);
		chk(v, dis[v]);
	}
	cout << ans.size() << ln;
	for (auto v : ans) cout << v << bb;
}

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