Submission #697204

#	Time	Username	Problem	Language	Result	Execution time	Memory
697204		flappybird	Capital City (JOI20_capital_city)	C++17	100 / 100	604 ms	43588 KiB

capital_city

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
#define MAX 201010
#define MAXS 20
#define INF 1000000000000000001
#define bb ' '
#define ln '\n'
#define Ln '\n'
#define MOD 1000000007
vector<int> adj[MAX];
int col[MAX];
int prt[MAX];
int num[MAX];
int vis[MAX];
int C[MAX];
int used[MAX];
int cvis[MAX];
void make_num(int x, int c, int p = 0) {
	col[x] = c;
	num[x] = 1;
	for (auto v : adj[x]) {
		if (col[v] == c) continue;
		if (vis[v]) continue;
		make_num(v, c, x);
		num[x] += num[v];
	}
}
void dfs(int x, int c, int p = 0) {
	prt[x] = p;
	used[x] = 0;
	for (auto v : adj[x]) {
		if (col[v] != c) continue;
		if (v == p) continue;
		if (vis[v]) continue;
		dfs(v, c, x);
	}
}
int cnt, ans, N, K;
vector<int> cs[MAX];
void make_tree(int x) {
	cnt++;
	make_num(x, cnt);
	int c = x;
	int n = num[x];
	while (1) {
		int changed = 0;
		for (auto v : adj[c]) {
			if (vis[v]) continue;
			if (num[c] < num[v]) continue;
			if (num[v] > n / 2) {
				changed = 1;
				c = v;
				break;
			}
		}
		if (!changed) break;
	}
	vector<int> all;
	queue<int> q;
	int sum = 0;
	dfs(c, cnt);
	q.push(C[c]);
	int pos = 1;
	used[c] = 1;
	while (q.size()) {
		int c = q.front();
		q.pop();
		if (cvis[c]) continue;
		cvis[c] = 1;
		all.push_back(c);
		sum++;
		for (auto v : cs[c]) {
			if (col[v] != cnt) {
				pos = 0;
				break;
			}
			while (1) {
				if (used[v]) break;
				q.push(C[v]);
				used[v] = 1;
				v = prt[v];
			}
		}
		if (!pos) break;
	}
	for (auto v : all) cvis[v] = 0;
	if (pos) ans = min(ans, sum);
	vis[c] = 1;
	for (auto v : adj[c]) if (!vis[v]) make_tree(v);
}
signed main() {
	ios::sync_with_stdio(false), cin.tie(0);
	int N, K;
	cin >> N >> K;
	ans = N;
	int i, a, b;
	for (i = 1; i < N; i++) {
		cin >> a >> b;
		adj[a].push_back(b);
		adj[b].push_back(a);
	}
	for (i = 1; i <= N; i++) cin >> C[i], cs[C[i]].push_back(i);
	make_tree(1);
	cout << ans - 1 << ln;
}

• Subtask 1: 1 / 1
• Subtask 2: 10 / 10
• Subtask 3: 30 / 30
• Subtask 4: 59 / 59