結果

問題 No.3113 The farthest point
ユーザー rii922
提出日時 2025-04-19 09:29:27
言語 C++23
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 300 ms / 2,000 ms
コード長 5,213 bytes
コンパイル時間 3,988 ms
コンパイル使用メモリ 292,048 KB
実行使用メモリ 51,032 KB
最終ジャッジ日時 2025-04-19 09:29:37
合計ジャッジ時間 10,214 ms
ジャッジサーバーID
（参考情報） 		judge5 / judge2
このコードへのチャレンジ
（要ログイン）
ファイルパターン 結果
sample AC * 3
other AC * 33
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>
#define rep(i, n) for(int i=0, i##_len=(n); i<i##_len; ++i)
#define reps(i, n) for(int i=1, i##_len=(n); i<=i##_len; ++i)
#define rrep(i, n) for(int i=((int)(n)-1); i>=0; --i)
#define rreps(i, n) for(int i=((int)(n)); i>0; --i)
#define all(v) (v).begin(), (v).end()
#define el '\n'
using namespace std;
using ll = long long;
using ull = unsigned long long;
using vi = vector<int>;
using vvi = vector<vector<int>>;
using vvvi = vector<vector<vector<int>>>;
using vl = vector<ll>;
using vvl = vector<vector<ll>>;
using vvvl = vector<vector<vector<ll>>>;
using vs = vector<string>;
using pi = pair<int, int>;
using pl = pair<ll, ll>;
template<class T> using min_priority_queue = priority_queue<T, vector<T>, greater<T>>;
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
template<class T> bool chmaxeq(T &a, const T &b) { if (a<=b) { a=b; return 1; } return 0; }
template<class T> bool chmineq(T &a, const T &b) { if (b<=a) { a=b; return 1; } return 0; }
bool yes(bool a=true) { cout << (a?"yes":"no") << el; return a; }
bool no(bool a=true) { cout << (a?"no":"yes") << el; return a; }
bool Yes(bool a=true) { cout << (a?"Yes":"No") << el; return a; }
bool No(bool a=true) { cout << (a?"No":"Yes") << el; return a; }
bool YES(bool a=true) { cout << (a?"YES":"NO") << el; return a; }
bool NO(bool a=true) { cout << (a?"NO":"YES") << el; return a; }
template<class T1, class T2> istream &operator>>(istream &is, pair<T1, T2> &p);
template<class T1, class T2> ostream &operator<<(ostream &os, const pair<T1, T2> &p);
template<class T> istream &operator>>(istream &is, vector<T> &v);
template<class T> ostream &operator<<(ostream &os, const vector<T> &v);
template<class T1, class T2>
istream &operator>>(istream &is, pair<T1, T2> &p) {
	return is >> p.first >> p.second;
}
template<class T1, class T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
	return os << p.first << ' ' << p.second;
}
template<class T>
istream &operator>>(istream &is, vector<T> &v) {
	int sz = v.size();
	for (int i = 0; i < sz; i++) is >> v[i];
	return is;
}
template<class T>
ostream &operator<<(ostream &os, const vector<T> &v) {
	int sz = v.size();
	for (int i = 0; i < sz; i++) {
		if (i) os << ' ';
		os << v[i];
	}
	return os;
}
void _main();
int main() { cin.tie(0); ios::sync_with_stdio(0); cout << fixed << setprecision(16); _main(); return 0; }


template<class S, S (*op)(S, S), S (*e)(), S (*put_vertex)(S, int), S (*put_edge)(S, int)>
struct rerooting {
	rerooting(int n) : _graph(n), _lprod(n), _rprod(n) {}
	int add_edge(int from, int to) {
		int pos = _graph[from].size();
		int rev_pos = _graph[to].size();
		int index = _nodes.size();
		_graph[from].push_back(node(to, rev_pos, index));
		_graph[to].push_back(node(from, pos, index));
		_nodes.push_back(node_memo(from, pos));
		return index;
	}
	vector<S> calc() {
		_dfs1();
		_dfs2();
		vector<S> res;
		for (int i = 0; i < _graph.size(); i++) res.push_back(put_vertex(_lprod[i][_graph[i].size()], i));
		return res;
	}
	S partial(int index, int s) {
		int from = _nodes[index].from;
		int pos = _nodes[index].pos;
		int to = _graph[from][pos].to;
		int rev_pos = _graph[from][pos].rev_pos;
		if (s != _graph[from][pos].to) {
			swap(from, to);
			swap(pos, rev_pos);
		}
		assert(s == _graph[from][pos].to);
		return put_vertex(op(_lprod[to][rev_pos], _rprod[to][rev_pos+1]), to);
	}
private:
	struct node {
		int to, rev_pos, index;
		S val;
		node(int to, int rev_pos, int index) : to(to), rev_pos(rev_pos), index(index), val(e()) {}
	};
	struct node_memo {
		int from, pos;
		node_memo(int from, int pos) : from(from), pos(pos) {}
	};
	vector<vector<node>> _graph;
	vector<node_memo> _nodes;
	vector<vector<S>> _lprod, _rprod;
	S _dfs1(int s=0, int p=-1) {
		int deg = _graph[s].size();
		S prod = e();
		for (int i = 0; i < deg; i++) {
			int t = _graph[s][i].to;
			if (t == p) continue;
			S partial = put_edge(_dfs1(t, s), _graph[s][i].index);
			_graph[s][i].val = partial;
			prod = op(prod, partial);
		}
		return put_vertex(prod, s);
	}
	void _dfs2(int s=0, int p=-1, S prod_par=e()) {
		int deg = _graph[s].size();
		_lprod[s].resize(deg+1, e());
		_rprod[s].resize(deg+1, e());
		S prod = e();
		for (int i = 0; i < deg; i++) {
			int t = _graph[s][i].to;
			if (t == p) _graph[s][i].val = put_edge(prod_par, _graph[s][i].index);
			prod = op(prod, _graph[s][i].val);
			_lprod[s][i+1] = prod;
		}
		prod = e();
		for (int i = deg-1; i >= 0; i--) {
			prod = op(prod, _graph[s][i].val);
			_rprod[s][i] = prod;
		}
		for (int i = 0; i < deg; i++) {
			int t = _graph[s][i].to;
			if (t == p) continue;
			_dfs2(t, s, put_vertex(op(_lprod[s][i], _rprod[s][i+1]), s));
		}
	}
};

vl w;
ll op(ll a, ll b) {
	return max(a, b);
}
ll e() {
	return 0;
}
ll put_vertex(ll x, int i) {
	return x;
}
ll put_edge(ll x, int i) {
	return x+w[i];
}

void _main() {
	ll N; cin >> N;
	w = vl(N-1);
	rerooting<ll, op, e, put_vertex, put_edge> rr(N);
	rep(i, N-1) {
		ll u, v; cin >> u >> v >> w[i];
		u--; v--;
		rr.add_edge(u, v);
	}
	ll ans = 0;
	for (auto &x : rr.calc()) chmax(ans, x);
	cout << ans << el;
}
0