This documentation is automatically generated by online-judge-tools/verification-helper
#define PROBLEM "http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_5_A"
#include "../../template/template.hpp"
#include "../../graph/tree/tree-diameter.hpp"
int main() {
int N;
cin >> N;
TreeDiameter< int > g(N);
g.read(N - 1, 0, true);
cout << g.build() << endl;
}
#line 1 "test/verify/aoj-grl-5-a.test.cpp"
#define PROBLEM "http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_5_A"
#line 1 "template/template.hpp"
#include<bits/stdc++.h>
using namespace std;
using int64 = long long;
const int mod = 1e9 + 7;
const int64 infll = (1LL << 62) - 1;
const int inf = (1 << 30) - 1;
struct IoSetup {
IoSetup() {
cin.tie(nullptr);
ios::sync_with_stdio(false);
cout << fixed << setprecision(10);
cerr << fixed << setprecision(10);
}
} iosetup;
template< typename T1, typename T2 >
ostream &operator<<(ostream &os, const pair< T1, T2 >& p) {
os << p.first << " " << p.second;
return os;
}
template< typename T1, typename T2 >
istream &operator>>(istream &is, pair< T1, T2 > &p) {
is >> p.first >> p.second;
return is;
}
template< typename T >
ostream &operator<<(ostream &os, const vector< T > &v) {
for(int i = 0; i < (int) v.size(); i++) {
os << v[i] << (i + 1 != v.size() ? " " : "");
}
return os;
}
template< typename T >
istream &operator>>(istream &is, vector< T > &v) {
for(T &in : v) is >> in;
return is;
}
template< typename T1, typename T2 >
inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
template< typename T1, typename T2 >
inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }
template< typename T = int64 >
vector< T > make_v(size_t a) {
return vector< T >(a);
}
template< typename T, typename... Ts >
auto make_v(size_t a, Ts... ts) {
return vector< decltype(make_v< T >(ts...)) >(a, make_v< T >(ts...));
}
template< typename T, typename V >
typename enable_if< is_class< T >::value == 0 >::type fill_v(T &t, const V &v) {
t = v;
}
template< typename T, typename V >
typename enable_if< is_class< T >::value != 0 >::type fill_v(T &t, const V &v) {
for(auto &e : t) fill_v(e, v);
}
template< typename F >
struct FixPoint : F {
explicit FixPoint(F &&f) : F(forward< F >(f)) {}
template< typename... Args >
decltype(auto) operator()(Args &&... args) const {
return F::operator()(*this, forward< Args >(args)...);
}
};
template< typename F >
inline decltype(auto) MFP(F &&f) {
return FixPoint< F >{forward< F >(f)};
}
#line 4 "test/verify/aoj-grl-5-a.test.cpp"
#line 2 "graph/tree/tree-diameter.hpp"
#line 2 "graph/graph-template.hpp"
/**
* @brief Graph Template(グラフテンプレート)
*/
template< typename T = int >
struct Edge {
int from, to;
T cost;
int idx;
Edge() = default;
Edge(int from, int to, T cost = 1, int idx = -1) : from(from), to(to), cost(cost), idx(idx) {}
operator int() const { return to; }
};
template< typename T = int >
struct Graph {
vector< vector< Edge< T > > > g;
int es;
Graph() = default;
explicit Graph(int n) : g(n), es(0) {}
size_t size() const {
return g.size();
}
void add_directed_edge(int from, int to, T cost = 1) {
g[from].emplace_back(from, to, cost, es++);
}
void add_edge(int from, int to, T cost = 1) {
g[from].emplace_back(from, to, cost, es);
g[to].emplace_back(to, from, cost, es++);
}
void read(int M, int padding = -1, bool weighted = false, bool directed = false) {
for(int i = 0; i < M; i++) {
int a, b;
cin >> a >> b;
a += padding;
b += padding;
T c = T(1);
if(weighted) cin >> c;
if(directed) add_directed_edge(a, b, c);
else add_edge(a, b, c);
}
}
inline vector< Edge< T > > &operator[](const int &k) {
return g[k];
}
inline const vector< Edge< T > > &operator[](const int &k) const {
return g[k];
}
};
template< typename T = int >
using Edges = vector< Edge< T > >;
#line 4 "graph/tree/tree-diameter.hpp"
/**
* @brief Tree-Diameter(木の直径)
* @docs docs/tree-diameter.md
*/
template< typename T = int >
struct TreeDiameter : Graph< T > {
public:
using Graph< T >::Graph;
using Graph< T >::g;
vector< Edge< T > > path;
T build() {
to.assign(g.size(), -1);
auto p = dfs(0, -1);
auto q = dfs(p.second, -1);
int now = p.second;
while(now != q.second) {
for(auto &e : g[now]) {
if(to[now] == e.to) {
path.emplace_back(e);
}
}
now = to[now];
}
return q.first;
}
explicit TreeDiameter(const Graph< T > &g) : Graph< T >(g) {}
private:
vector< int > to;
pair< T, int > dfs(int idx, int par) {
pair< T, int > ret(0, idx);
for(auto &e : g[idx]) {
if(e.to == par) continue;
auto cost = dfs(e.to, idx);
cost.first += e.cost;
if(ret < cost) {
ret = cost;
to[idx] = e.to;
}
}
return ret;
}
};
#line 6 "test/verify/aoj-grl-5-a.test.cpp"
int main() {
int N;
cin >> N;
TreeDiameter< int > g(N);
g.read(N - 1, 0, true);
cout << g.build() << endl;
}