#1187626 (C++23) No.3719 Share the Tree

• 問題: No.3719 Share the Tree
• ユーザー: 👑 qand
• 提出日時: 2026-09-18 22:16:41
• 言語: C++23 (gcc 15.3.0 + boost 1.92.0 + ACL)
• 結果: AC
• 実行時間: 185 ms / 2,000 ms
• コード長: 5,484 bytes
• コンパイル時間: 4,889 ms
• コンパイル使用メモリ: 381,064 KB
• 実行使用メモリ: 6,528 KB
• 平均クエリ数: 2.00
• 最終ジャッジ日時: 2026-09-18 22:16:50
• 合計ジャッジ時間: 8,624 ms
• ジャッジサーバーID （参考情報）: judge1_0 / judge3_0

ファイルパターン	結果
sample	AC * 1
other	AC * 26

ソースコード

#include <bits/stdc++.h>
// #include <boost/multiprecision/cpp_int.hpp>
using namespace std;
using std::cerr, std::cin, std::cout;
#define vec vector
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using mint = atcoder::modint998244353;
std::istream &operator>>(std::istream &is, mint &a) {
	long long t;
	is >> t;
	a = t;
	return is;
}
std::ostream &operator<<(std::ostream &os, mint a) { return os << a.val(); }
// vec<mint> operator*(const vec<mint> &a, const vec<mint> &b) { return a.empty() || b.empty() ? vec<mint>() : atcoder::convolution(a, b); }
// vec<mint> &operator*=(vec<mint> &a, const vec<mint> &b) { return a = a * b; }
#endif
typedef long double ld;
#if LONG_MAX == 2147483647L
#undef long
#define long long long
#endif
#define uint unsigned int
#define ulong 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()), a.shrink_to_fit()
#define sz(a) static_cast<int>(a.size())
#ifndef DEBUG
#define cerr \
	if (false) cerr
// #undef assert
// #define assert(...) void(0)
#undef endl
#define endl '\n'
#endif
ostream &operator<<(ostream &os, __int128_t value) {
	ostream::sentry s(os);
	if (s) {
		__uint128_t tmp = value < 0 ? -value : value;
		char buffer[128];
		char *d = std::end(buffer);
		do {
			--d;
			*d = "0123456789"[tmp % 10];
			tmp /= 10;
		} while (tmp != 0);
		if (value < 0) --d, *d = '-';
		const int len = std::end(buffer) - d;
		if (os.rdbuf()->sputn(d, len) != len) os.setstate(std::ios_base::badbit);
	}
	return os;
}
template <typename T, typename S>
ostream &operator<<(ostream &os, pair<T, S> a) {
	return os << a.first << ' ' << a.second;
};
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, typename S>
istream &operator>>(istream &is, pair<T, S> &a) {
	return is >> a.first >> a.second;
}
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--;
}
void init(), solve();
int main() {
	// srand((unsigned)time(NULL));
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	cout << fixed << setprecision(20);
	cerr << fixed << setprecision(20);
	init();
	int t = 1;
	// cin >> t;
	while (t--) solve();
}
void init() {}
// https://kyopro.hateblo.jp/entry/2019/01/16/200456
struct Graph {
	size_t n;
	std::vector<std::vector<int>> adj;

	Graph(size_t _n) : n(_n), adj(_n) {}
	void add_edge(const int u, const int v) {
		adj[u].push_back(v);
		adj[v].push_back(u);
	}
};

std::vector<int> TreeToPruferSequence(const Graph &tree) {
	if (tree.n <= 2) return std::vector<int>{};

	std::priority_queue<int, std::vector<int>, std::greater<int>> que;
	std::vector<int> deg(tree.n);
	for (size_t v = 0; v < tree.n; ++v) {
		deg[v] = tree.adj[v].size();
		if (deg[v] == 1) que.push(v);
	}

	std::vector<int> seq;
	seq.reserve(tree.n - 2);
	while (seq.size() + 2 < tree.n) {
		const int leaf = que.top();
		que.pop();
		for (int u : tree.adj[leaf]) {
			if (deg[u] != 0) {
				seq.push_back(u);
				--deg[u];
				if (deg[u] == 1) que.push(u);
				break;
			}
		}
		--deg[leaf];
	}

	return seq;
}
Graph PruferSequenceToTree(const std::vector<int> seq) {
	const int n = seq.size() + 2;
	std::vector<int> deg(n, 1);
	for (const int v : seq) ++deg[v];

	std::priority_queue<int, std::vector<int>, std::greater<int>> que;
	for (int v = 0; v < n; ++v)
		if (deg[v] == 1) que.push(v);

	Graph tree(n);
	for (const int v : seq) {
		const int u = que.top();
		que.pop();
		tree.add_edge(v, u);
		--deg[v];
		--deg[u];
		if (deg[v] == 1) que.push(v);
	}

	const int lst = que.top();
	que.pop();
	tree.add_edge(lst, que.top());
	return tree;
}

void solve_alice() {
	int n;
	cin >> n;
	cout << n - 2 << '\n'
		 << flush;
	Graph g(n);
	rep(i, n - 1) {
		int u, v;
		cin >> u >> v;
		u--, v--;
		g.add_edge(u, v);
	}
	auto a = TreeToPruferSequence(g);
	for (int &v : a) v++;
	cout << a << '\n'
		 << flush;
}
void solve_bob() {
	int n;
	cin >> n;
	cout << n - 2 << '\n'
		 << flush;
	vec<int> a(n - 2);
	cin >> a;
	for (int &v : a) v--;
	auto g = PruferSequenceToTree(a);
	rep(i, n) for (int j : g.adj[i]) {
		if (j < i)
			cout << j + 1 << ' ' << i + 1 << '\n'
				 << flush;
	}
}
void solve() {
	string s;
	cin >> s;
	if (s[0] == 'A') solve_alice();
	else solve_bob();
}