結果

問題 No.3206 う　し　た　ウ　ニ　木　あ　く　ん　笑
ユーザー 遭難者
提出日時 2025-07-17 13:32:59
言語 C++23
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 537 ms / 3,000 ms
コード長 6,090 bytes
コンパイル時間 6,672 ms
コンパイル使用メモリ 335,800 KB
実行使用メモリ 179,016 KB
最終ジャッジ日時 2025-07-17 13:33:16
合計ジャッジ時間 13,454 ms
ジャッジサーバーID
（参考情報） 		judge2 / judge3
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 2
other AC * 30
権限があれば一括ダウンロードができます

ソースコード

diff # 

#include <bits/stdc++.h>
using namespace std;
using std::cerr;
using std::cin;
using std::cout;
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using mint = atcoder::modint998244353;
istream &operator>>(istream &is, mint &a) {
	long long t;
	is >> t;
	a = t;
	return is;
}
ostream &operator<<(ostream &os, mint a) { return os << a.val(); }
#endif
typedef long double ld;
#define long long long
#define uint unsigned int
#define ull unsigned long
#define overload3(a, b, c, name, ...) name
#define rep3(i, a, b) for (int i = (a); i < (b); i++)
#define rep2(i, n) rep3(i, 0, n)
#define rep1(n) rep2(__i, n)
#define rep(...) overload3(__VA_ARGS__, rep3, rep2, rep1)(__VA_ARGS__)
#define per3(i, a, b) for (int i = (b) - 1; i >= (a); i--)
#define per2(i, n) per3(i, 0, n)
#define per1(n) per2(__i, n)
#define per(...) overload3(__VA_ARGS__, per3, per2, per1)(__VA_ARGS__)
#define all(a) a.begin(), a.end()
#define UNIQUE(a)                                                              \
	sort(all(a));                                                              \
	a.erase(unique(all(a)), a.end())
#define sz(a) (int)a.size()
#define vec vector
#ifndef DEBUG
#define cerr                                                                   \
	if (0)                                                                     \
	cerr
// #undef assert
// #define assert(...) void(0)
#undef endl
#define endl '\n'
#endif
template <typename T> ostream &operator<<(ostream &os, vector<T> a) {
	const int n = a.size();
	rep(i, n) {
		os << a[i];
		if (i + 1 != n)
			os << " ";
	}
	return os;
}
template <typename T, size_t n>
ostream &operator<<(ostream &os, array<T, n> a) {
	rep(i, n) {
		os << a[i];
		if (i + 1 != n)
			os << " ";
	}
	return os;
}
template <typename T> istream &operator>>(istream &is, vector<T> &a) {
	for (T &i : a)
		is >> i;
	return is;
}
template <typename T, typename S> bool chmin(T &x, S y) {
	if ((T)y < x) {
		x = (T)y;
		return true;
	}
	return false;
}
template <typename T, typename S> bool chmax(T &x, S y) {
	if (x < (T)y) {
		x = (T)y;
		return true;
	}
	return false;
}
template <typename T> void operator++(vector<T> &a) {
	for (T &i : a)
		++i;
}
template <typename T> void operator--(vector<T> &a) {
	for (T &i : a)
		--i;
}
template <typename T> void operator++(vector<T> &a, int) {
	for (T &i : a)
		i++;
}
template <typename T> void operator--(vector<T> &a, int) {
	for (T &i : a)
		i--;
}

/*
r を根として固定
V dfs(vertex v){
   E prod = e();
   for ( c in child(v) ){
	   prod = merge(prod, put_edge(dfs(c),idx(v,c)));
   }
   return put_vertex(prod, v);
}
r=0,...,n-1 に対し r を根として dfs(r) の値を求める
*/
// add_edge -> build -> reroot に答え
template <class E, class V, E (*merge)(E, E), E (*e)(), E (*put_edge)(V, int),
		  V (*put_vertex)(E, int)>
struct RerootingDP {
	struct edge {
		int to, idx, xdi;
	};
	RerootingDP(int n_ = 0) : n(n_), inner_edge_id(0) {
		es.resize(2 * n - 2);
		start.resize(2 * n - 2);
		if (n == 1)
			es_build();
	}
	void add_edge(int u, int v, int idx, int xdi) {
		start[inner_edge_id] = u;
		es[inner_edge_id] = {v, idx, xdi};
		inner_edge_id++;
		start[inner_edge_id] = v;
		es[inner_edge_id] = {u, xdi, idx};
		inner_edge_id++;
		if (inner_edge_id == 2 * n - 2) {
			es_build();
		}
	}
	vector<V> build(int root_ = 0) {
		root = root_;
		vector<V> subdp(n);
		subdp[0] = put_vertex(e(), 0);
		outs.resize(n);
		vector<int> geta(n + 1, 0);
		for (int i = 0; i < n; i++)
			geta[i + 1] = start[i + 1] - start[i] - 1;
		geta[root + 1]++;
		for (int i = 0; i < n; i++)
			geta[i + 1] += geta[i];
		auto dfs = [&](auto sfs, int v, int f) -> void {
			E val = e();
			for (int i = start[v]; i < start[v + 1]; i++) {
				if (es[i].to == f) {
					swap(es[start[v + 1] - 1], es[i]);
				}
				if (es[i].to == f)
					continue;
				sfs(sfs, es[i].to, v);
				E nval = put_edge(subdp[es[i].to], es[i].idx);
				outs[geta[v]++] = nval;
				val = merge(val, nval);
			}
			subdp[v] = put_vertex(val, v);
		};
		dfs(dfs, root, -1);
		return subdp;
	}
	vector<V> reroot() {
		vector<E> reverse_edge(n);
		reverse_edge[root] = e();
		vector<V> answers(n);
		auto dfs = [&](auto sfs, int v) -> void {
			int le = outs_start(v);
			int ri = outs_start(v + 1);
			int siz = ri - le;
			vector<E> rui(siz + 1);
			rui[siz] = e();
			for (int i = siz - 1; i >= 0; i--) {
				rui[i] = merge(outs[le + i], rui[i + 1]);
			}
			answers[v] = put_vertex(merge(rui[0], reverse_edge[v]), v);
			E lui = e();
			for (int i = 0; i < siz; i++) {
				V rdp = put_vertex(
					merge(merge(lui, rui[i + 1]), reverse_edge[v]), v);
				reverse_edge[es[start[v] + i].to] =
					put_edge(rdp, es[start[v] + i].xdi);
				lui = merge(lui, outs[le + i]);
				sfs(sfs, es[start[v] + i].to);
			}
		};
		dfs(dfs, root);
		return answers;
	}

  private:
	int n, root, inner_edge_id;
	vector<E> outs;
	vector<edge> es;
	vector<int> start;
	int outs_start(int v) {
		int res = start[v] - v;
		if (root < v)
			res++;
		return res;
	}
	void es_build() {
		vector<edge> nes(2 * n - 2);
		vector<int> nstart(n + 2, 0);
		for (int i = 0; i < 2 * n - 2; i++)
			nstart[start[i] + 2]++;
		for (int i = 0; i < n; i++)
			nstart[i + 1] += nstart[i];
		for (int i = 0; i < 2 * n - 2; i++)
			nes[nstart[start[i] + 1]++] = es[i];
		swap(es, nes);
		swap(start, nstart);
	}
};
using vi = vec<int>;
vi merge(vi a, vi b) {
	for (auto i : b)
		a.push_back(i);
	return a;
}
vi e() { return {0}; }
vi put_edge(vi a, int) { return {1 + *max_element(all(a))}; }
vi put_vertex(vi a, int) { return a; }
void solve() {
	int n;
	cin >> n;
	RerootingDP<vi, vi, merge, e, put_edge, put_vertex> g(n);
	rep(i, n - 1) {
		int u, v;
		cin >> u >> v;
		u--, v--;
		g.add_edge(u, v, -1, -1);
	}
	g.build();
	auto res = g.reroot();
	long ans = 0;
	for (vi &a : res) {
		sort(all(a), greater<int>());
		rep(i, sz(a)) { chmax(ans, (i + 1) * a[i]); }
	}
	cout << ans + 1 << endl;
}
int main() {
	// srand((unsigned)time(NULL));
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	cout << fixed << setprecision(20);
	int t = 1;
	// cin >> t;
	while (t--)
		solve();
}
0