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답안 #930162

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
930162 2024-02-18T18:52:41 Z ParsaS 수도 (JOI20_capital_city) C++17
0 / 100
 90 ms 27988 KB 
// In the name of God
#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define fi first
#define se second
#define mp make_pair
typedef long long ll;
const int N = 2e5 + 5, lg = 20;
int n, k, a[N];
vector<int> adj[N], vec[N], G[N];
int up[N][lg], tin[N], tout[N], T, h[N];
int f[N], par[N];

void dfs(int v, int p) {
	up[v][0] = p;
	par[v] = p;
	for (int i = 1; i < lg; i++) {
		up[v][i] = up[up[v][i - 1]][i - 1];
	}
	tin[v] = ++T;
	for (auto u : adj[v]) {
		if (u != p) {
			h[u] = h[v] + 1;
			dfs(u, v);
		}
	}
	tout[v] = ++T;
}

bool anc(int v, int u) {
	return tin[v] <= tin[u] && tout[v] >= tout[u];
}

int lca(int v, int u) {
	if (tin[v] > tin[u]) swap(v, u);
	if (anc(v, u)) return v;

	for (int i = lg - 1; i >= 0; i--) {
		if (!anc(up[u][i], v)) {
			u = up[u][i];
		}
	}
	return up[u][0];
}

vector<int> V;
int out[N];

void dfs2(int v, int p) {
	vector<int> dat;
	while (!V.empty() && h[f[V.back()]] >= h[f[v]]) {
		dat.pb(V.back());
		V.pop_back();
	}
	V.pb(v);

	int l = -1, r = V.size() - 1;
	while (r - l > 1) {
		int mid = (l + r) >> 1;
		if (h[V[mid]] >= h[f[v]])
			r = mid;
		else l = mid;
	}
	if (a[v] != a[V[r]]) {
		out[a[v]]++;
		G[a[V[r]]].pb(a[v]);
	}
	for (auto u : adj[v]) {
		if (u != p)
			dfs2(u, v);
	}
	V.pop_back();
	while (!dat.empty()) {
		V.pb(dat.back());
		dat.pop_back();
	}
}

int F[N];
bool vis[N];

void dfs3(int v) {
	vis[v] = true;
	for (auto u : G[v]) {
		if (vis[u]) continue;
		if (h[F[u]] > h[F[v]])
			F[u] = F[v];
		dfs3(u);
	}
}
int col[N];


void solve() {
	cin >> n >> k;
	for (int i = 0; i < n - 1; i++) {
		int v, u; cin >> v >> u;
		adj[v].pb(u), adj[u].pb(v);
	}
	for (int i = 1; i <= n; i++) {
		cin >> a[i];
		vec[a[i]].pb(i);
	}
	if (n > 20) return;

	dfs(1, 1);

	for (int i = 1; i <= k; i++) {
		int u = vec[i].back();
		for (auto v : vec[i]) {
			u = lca(u, v);
		}
		for (auto v : vec[i])
			f[v] = u;
		F[i] = u;
	}

	//dfs2(1, 0);
	for (int v = 1; v <= n; v++) {
		int u = par[v], mx = v;
		while (u != f[v] && v != f[v]) {
			if (h[f[u]] < h[f[mx]]) {
				mx = u;
			}
			u = par[u];
		}
		u = mx;
		if (a[v] != a[u]) {
			G[a[u]].pb(a[v]);
			out[a[v]]++;
		}
	}
	vector<pair<int, int> > ver;
	for (int i = 1; i <= k; i++) {
		if (out[i] == 0) {
			ver.pb(mp(h[vec[i].back()], f[vec[i].back()]));
			dfs3(i);
		}
	}

	sort(ver.begin(), ver.end(), greater<pair<int, int> >());
	int ans = 1e9;
	for (auto [tmp, v] : ver) {
		if (col[a[v]])
			continue;
		queue<int> q;
		q.push(a[v]);
		col[a[v]] = a[v];
		bool ok = true;
		int cnt = 0;
		
		while (!q.empty()) {
			int c = q.front();
			q.pop();

			if (col[c] != a[v]) {
				ok = false;
				break;
			}
			for (auto w : vec[c]) {
				if (w == v) continue;
				int u = par[w];
				if (col[a[u]] == 0) {
					col[a[u]] = a[v];
					cnt++;
					q.push(a[u]);
				}
			}
		}
		if (ok)
			ans = min(ans, cnt);
	}
	cout << ans << '\n';
}

int32_t main() {
	ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);

	int tc = 1; // cin >> tc;
	while (tc--) {
		solve();
	}

	return 0;
}

Subtask #1
0 / 1.0

# 결과 실행 시간 메모리 Grader output
1 Correct 6 ms 22108 KB Output is correct
2 Correct 6 ms 22108 KB Output is correct
3 Correct 6 ms 22104 KB Output is correct
4 Incorrect 6 ms 22108 KB Output isn't correct
5 Halted 0 ms 0 KB -

Subtask #2
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 6 ms 22108 KB Output is correct
2 Correct 6 ms 22108 KB Output is correct
3 Correct 6 ms 22104 KB Output is correct
4 Incorrect 6 ms 22108 KB Output isn't correct
5 Halted 0 ms 0 KB -

Subtask #3
0 / 30.0

# 결과 실행 시간 메모리 Grader output
1 Incorrect 90 ms 27988 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #4
0 / 59.0

# 결과 실행 시간 메모리 Grader output
1 Correct 6 ms 22108 KB Output is correct
2 Correct 6 ms 22108 KB Output is correct
3 Correct 6 ms 22104 KB Output is correct
4 Incorrect 6 ms 22108 KB Output isn't correct
5 Halted 0 ms 0 KB -