Submission #682053

#	Time	Username	Problem	Language	Result	Execution time	Memory
682053		Kahou	Mergers (JOI19_mergers)	C++14	100 / 100	1081 ms	140128 KiB

mergers

/* In the name of God, aka Allah */
// let this be mytemp.cpp
#include<bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define endl '\n'
#define mk make_pair
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int N = 5e5 + 50;
int n, k, cnt[N], ans, par[N];
int pr[N], sz[N];
int d[N];
bool mark[N];
vector<int> adj[N];
map<int, int> mp[N];

int getroot(int u) {
	if (pr[u] == u) return u;
	return pr[u] = getroot(pr[u]);
}
void uniset(int u, int v) {
	u = getroot(u);
	v = getroot(v);
	if (u == v) return;
	if (sz[u] < sz[v]) swap(u, v);
	pr[v] = u;
	sz[u] += sz[v];
}
void dfs(int u, int p) {
	par[u] = p;
	for (int v:adj[u]) {
		if (v == p) continue;
		dfs(v, u);

		if (!mp[v].empty()) uniset(u, v);
		else mark[v] = 1;

		if (mp[u].size() < mp[v].size()) swap(mp[u], mp[v]);
		for (pii x:mp[v]) {
			mp[u][x.F] += x.S;
			if (mp[u][x.F] == cnt[x.F]) mp[u].erase(x.F);
		}
		mp[v].clear();
	}
}
void solve() {
	cin >> n >> k;
	for (int i = 1; i <= n-1; i++) {
		int u, v;
		cin >> u >> v;
		adj[u].push_back(v);
		adj[v].push_back(u);
	}
	for (int u = 1; u <= n; u++) {
		int c;
		cin >> c;
		mp[u][c]++;
		cnt[c]++;
		pr[u] = u;
		sz[u] = 1;
	}
	for (int u = 1; u <= n; u++) {
		if (mp[u].begin()->S == cnt[mp[u].begin()->F]) mp[u].clear();
	}
	dfs(1, 0);
	for (int u = 1; u <= n; u++) {
		if (mark[u]) {
			d[getroot(u)]++;
			d[getroot(par[u])]++;
		}
	}
	set<int> st;
	for (int u = 1; u <= n; u++) {
		if (d[u] == 1) st.insert(u);
	}
	cout << (st.size()+1)/2 << endl;
}

int main() {
	ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	solve();
	return 0;
}

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