제출 #376884

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
376884		casperwang	Mergers (JOI19_mergers)	C++14	48 / 100	3083 ms	30852 KiB

mergers

#include <bits/stdc++.h>
#define pb emplace_back
using namespace std;
#define debug(args...) kout("[ " + string(#args) + " ]", args)
void kout() { cerr << endl; }
template <class T, class ...U> void kout(T a, U ...b) { cerr << a << ' ',kout(b...); }
template <class T> void pary(T L, T R) { while (L != R) cerr << *L << " \n"[++L==R]; }

const int MAXN = 500000;
int N, K;
int a, b;
vector <int> path[MAXN+1];
vector <int> G[MAXN+1];
int v[MAXN+1];
int dsu[MAXN+1];
int sze[MAXN+1];
bool vis[MAXN+1];
int k[MAXN+1];
int ans = 0;

int fnd(int a) {
	return dsu[a] == a ? a : dsu[a] = fnd(dsu[a]);
}

void Merge(int a, int b) {
	a = fnd(a), b = fnd(b);
	if (a == b) return;
	if (sze[a] > sze[b]) {
		dsu[b] = a;
		sze[a] += sze[b];
	} else {
		dsu[a] = b;
		sze[b] += sze[a];
	}
}

void BFS(int st) {
	for (int i = 1; i <= N; i++)
		k[i] = 0;
	k[st] = st;
	queue <int> nxt;
	nxt.push(st);
	while (nxt.size()) {
		int now = nxt.front();
		nxt.pop();
		for (int i : path[now]) {
			if (i == k[now]) continue;
			k[i] = now;
			nxt.push(i);
		}
	}
	for (int i = 1; i <= N; i++) {
		if (v[i] != v[st]) continue;
		int t = i;
		while (k[t] != t) {
			if (fnd(t) == fnd(st)) break;
			Merge(t, k[t]);
			t = k[t];
		}
	}
	return;
}

signed main() {
	ios_base::sync_with_stdio(0), cin.tie(0);
	cin >> N >> K;
	for (int i = 1; i < N; i++) {
		cin >> a >> b;
		path[a].pb(b);
		path[b].pb(a);
	}
	for (int i = 1; i <= N; i++) {
		cin >> v[i];
		dsu[i] = i;
		sze[i] = 1;
	}
	for (int i = 1; i <= N; i++) {
		if (vis[v[i]]) continue;
		BFS(i);
		vis[v[i]] = true;
	}
	for (int i = 1; i <= N; i++) {
		for (int j : path[i]) {
			if (fnd(i) == fnd(j)) continue;
			G[fnd(i)].pb(fnd(j));
		}
	}
	for (int i = 1; i <= N; i++) {
		if (fnd(i) != i || !G[i].size()) continue;
		bool flag = true;
		for (int j : G[i])
			flag &= (j == G[i][0]);
		if (flag) ans++;
	}
	cout << (ans+1)/2 << '\n';
	return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 24 / 24
• Subtask 3: 14 / 14
• Subtask 4: 0 / 22
• Subtask 5: 0 / 30