mmrz's library

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:heavy_check_mark: verify/yosupo/tree_diameter.test.cpp

Depends on

Code

#define PROBLEM "https://judge.yosupo.jp/problem/tree_diameter"

#include "./../../template/template.hpp"
#include "./../../graph/tree_diameter.hpp"

using namespace mmrz;

void mmrz::solve(){
	int n;
	cin >> n;
	vector<vector<pair<int, ll>>> g(n);
	rep(i, n-1){
		int a, b, c;
		cin >> a >> b >> c;
		g[a].eb(b, c);
		g[b].eb(a, c);
	}

	auto [diameter, path] = tree_diameter(g);

	cout << diameter << " " << len(path) << '\n';
	rep(i, len(path))cout << path[i] << " \n"[i == len(path)-1];
}
#line 1 "verify/yosupo/tree_diameter.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/tree_diameter"

#line 1 "template/template.hpp"
# include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
const double pi = acos(-1);
template<class T>constexpr T inf() { return ::std::numeric_limits<T>::max(); }
template<class T>constexpr T hinf() { return inf<T>() / 2; }
template <typename T_char>T_char TL(T_char cX) { return tolower(cX); }
template <typename T_char>T_char TU(T_char cX) { return toupper(cX); }
template<class T> bool chmin(T& a,T b) { if(a > b){a = b; return true;} return false; }
template<class T> bool chmax(T& a,T b) { if(a < b){a = b; return true;} return false; }
int popcnt(unsigned long long n) { int cnt = 0; for (int i = 0; i < 64; i++)if ((n >> i) & 1)cnt++; return cnt; }
int d_sum(ll n) { int ret = 0; while (n > 0) { ret += n % 10; n /= 10; }return ret; }
int d_cnt(ll n) { int ret = 0; while (n > 0) { ret++; n /= 10; }return ret; }
ll gcd(ll a, ll b) { if (b == 0)return a; return gcd(b, a%b); };
ll lcm(ll a, ll b) { ll g = gcd(a, b); return a / g*b; };
ll MOD(ll x, ll m){return (x%m+m)%m; }
ll FLOOR(ll x, ll m) {ll r = (x%m+m)%m; return (x-r)/m; }
template<class T> using dijk = priority_queue<T, vector<T>, greater<T>>;
# define all(qpqpq)           (qpqpq).begin(),(qpqpq).end()
# define UNIQUE(wpwpw)        (wpwpw).erase(unique(all((wpwpw))),(wpwpw).end())
# define LOWER(epepe)         transform(all((epepe)),(epepe).begin(),TL<char>)
# define UPPER(rprpr)         transform(all((rprpr)),(rprpr).begin(),TU<char>)
# define rep(i,upupu)         for(ll i = 0, i##_len = (upupu);(i) < (i##_len);(i)++)
# define reps(i,opopo)        for(ll i = 1, i##_len = (opopo);(i) <= (i##_len);(i)++)
# define len(x)                ((ll)(x).size())
# define bit(n)               (1LL << (n))
# define pb push_back
# define eb emplace_back
# define exists(c, e)         ((c).find(e) != (c).end())

struct INIT{
	INIT(){
		std::ios::sync_with_stdio(false);
		std::cin.tie(0);
		cout << fixed << setprecision(20);
	}
}INIT;

namespace mmrz {
	void solve();
}

int main(){
	mmrz::solve();
}
#line 2 "graph/tree_diameter.hpp"

#line 7 "graph/tree_diameter.hpp"

template<typename T=long long>
std::pair<T, std::vector<int>> tree_diameter(const std::vector<std::vector<std::pair<int, T>>> &g){
	int n = (int)g.size();
	std::vector dis(n, std::numeric_limits<T>::max());
	std::queue<int> q;
	dis[0] = 0;
	q.push(0);

	while(not q.empty()){
		int v = q.front();
		q.pop();
		for(auto [to, c] : g[v]){
			if(dis[to] != std::numeric_limits<T>::max())continue;
			dis[to] = dis[v]+c;
			q.push(to);
		}
	}

	int r1 = -1;
	T mx = 0;
	for(int v = 0;v < n;v++){
		if(chmax(mx, dis[v])){
			r1 = v;
		}
	}

	dis.assign(n, std::numeric_limits<T>::max());
	std::vector<int> par(n, -1);
	dis[r1] = 0;
	q.push(r1);

	while(not q.empty()){
		int v = q.front();
		q.pop();
		for(auto [to, c] : g[v]){
			if(dis[to] != std::numeric_limits<T>::max())continue;
			dis[to] = dis[v]+c;
			par[to] = v;
			q.push(to);
		}
	}

	int r2 = -1;
	T diameter = 0;
	for(int v = 0;v < n;v++){
		if(chmax(diameter, dis[v])){
			r2 = v;
		}
	}

	std::vector<int> path;
	for(int cur = r2;cur != -1;cur = par[cur]){
		path.emplace_back(cur);
	}

	return {diameter, path};
}

std::pair<int, std::vector<int>> tree_diameter(const std::vector<std::vector<int>> &g_unweighted){
	int n = (int)g_unweighted.size();
	std::vector<std::vector<std::pair<int, int>>> g(n);

	for(int u = 0;u < n;u++){
		for(int v : g_unweighted[u]){
			g[u].emplace_back(v, 1);
			g[v].emplace_back(u, 1);
		}
	}
	return tree_diameter(g);
}
#line 5 "verify/yosupo/tree_diameter.test.cpp"

using namespace mmrz;

void mmrz::solve(){
	int n;
	cin >> n;
	vector<vector<pair<int, ll>>> g(n);
	rep(i, n-1){
		int a, b, c;
		cin >> a >> b >> c;
		g[a].eb(b, c);
		g[b].eb(a, c);
	}

	auto [diameter, path] = tree_diameter(g);

	cout << diameter << " " << len(path) << '\n';
	rep(i, len(path))cout << path[i] << " \n"[i == len(path)-1];
}
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