verify/verify-aoj-grl/aoj-grl-5-a-dynamic-rerooting.test.cpp

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Last update: 2024-05-03 23:21:26+09:00
Problem: http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_5_A

Depends on

Code

#define PROBLEM "http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_5_A"
//
#include "../../template/template.hpp"
//
#include "../../tree/dynamic-rerooting.hpp"
using namespace Nyaan;

struct HalfPath {
  ll d;
  int u;
  friend HalfPath max(const HalfPath &lhs, const HalfPath &rhs) {
    if (lhs.d != rhs.d) return lhs.d > rhs.d ? lhs : rhs;
    return lhs.u > rhs.u ? lhs : rhs;
  }
};
struct Path {
  ll d;
  int u, v;
  friend Path max(const Path &lhs, const Path &rhs) {
    if (lhs.d != rhs.d) return lhs.d > rhs.d ? lhs : rhs;
    if (lhs.u != rhs.u) return lhs.u > rhs.u ? lhs : rhs;
    return lhs.v > rhs.v ? lhs : rhs;
  }
};
struct L {
  Path dia;
  HalfPath d1, d2;
};
struct H {
  Path dia;
  HalfPath pd, cd;
  ll p_to_c;
  int p, c;
};
using I = pair<ll, int>;
H vertex(const I &xi) {
  auto [x, i] = xi;
  H r;
  r.dia = {x, i, i};
  r.pd = r.cd = {x, i};
  r.p_to_c = x;
  r.p = r.c = i;
  return r;
}
H compress(const H &p, const H &c) {
  H r;
  r.dia = max(max(p.dia, c.dia), {p.cd.d + c.pd.d, p.cd.u, c.pd.u});
  r.pd = max(p.pd, {p.p_to_c + c.pd.d, c.pd.u});
  r.cd = max(c.cd, {c.p_to_c + p.cd.d, p.cd.u});
  r.p_to_c = p.p_to_c + c.p_to_c;
  r.p = p.p, r.c = c.c;
  return r;
}
L rake(const L &a, const L &b) {
  L r;
  r.dia = max(a.dia, b.dia);
  if (a.d1.d > b.d1.d) {
    r.d1 = a.d1;
    r.d2 = max(a.d2, b.d1);
  } else {
    r.d1 = b.d1;
    r.d2 = max(b.d2, a.d1);
  }
  return r;
}
L add_edge(const H &a) {
  L r;
  r.dia = a.dia;
  r.d1 = a.pd;
  r.d2 = {0, -1};
  return r;
}
H add_vertex(const L &a, const I &xi) {
  auto [x, i] = xi;
  H r;
  r.dia = max(a.dia, {a.d1.d + x + a.d2.d, a.d1.u, a.d2.u});
  r.pd = r.cd = {a.d1.d + x, a.d1.u};
  r.p_to_c = x;
  r.p = r.c = i;
  return r;
}

using DD =
    TopTree<H, L, I, vertex, compress, rake, add_edge, add_vertex>;

void q() {
  int N;
  cin >> N;
  DD lct;
  vector<vector<pair<int, int> > > g(N);
  for (int i = 1; i < N; i++) {
    int x, y, z;
    cin >> x >> y >> z;
    g[x].emplace_back(y, z);
    g[y].emplace_back(x, z);
  }
  vector<typename DD::NP> vs(N), es(N);
  auto dfs = [&](auto rec, int idx, int par) -> void {
    vs[idx] = lct.alloc(make_pair(0, idx));
    for (auto &e : g[idx]) {
      if (e.first == par) continue;
      rec(rec, e.first, idx);
      es[e.first] = lct.alloc(make_pair(e.second, -1));
      lct.link(vs[e.first], es[e.first]);
      lct.link(es[e.first], vs[idx]);
    }
  };
  dfs(dfs, 0, -1);

  set<long long> anss;
  for (int i = 0; i < N; i++) {
    long long d = lct.query(vs[i]).dia.d;
    anss.emplace(d);
  }
  if (anss.size() != 1u) exit(1);
  cout << *begin(anss) << endl;
}

void Nyaan::solve() {
  int t = 1;
  // in(t);
  while (t--) q();
}

#line 1 "verify/verify-aoj-grl/aoj-grl-5-a-dynamic-rerooting.test.cpp"
#define PROBLEM "http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_5_A"
//
#line 2 "template/template.hpp"
using namespace std;

// intrinstic
#include <immintrin.h>

#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cfenv>
#include <cfloat>
#include <chrono>
#include <cinttypes>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdarg>
#include <cstddef>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <deque>
#include <fstream>
#include <functional>
#include <initializer_list>
#include <iomanip>
#include <ios>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <streambuf>
#include <string>
#include <tuple>
#include <type_traits>
#include <typeinfo>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

// utility
#line 1 "template/util.hpp"
namespace Nyaan {
using ll = long long;
using i64 = long long;
using u64 = unsigned long long;
using i128 = __int128_t;
using u128 = __uint128_t;

template <typename T>
using V = vector<T>;
template <typename T>
using VV = vector<vector<T>>;
using vi = vector<int>;
using vl = vector<long long>;
using vd = V<double>;
using vs = V<string>;
using vvi = vector<vector<int>>;
using vvl = vector<vector<long long>>;
template <typename T>
using minpq = priority_queue<T, vector<T>, greater<T>>;

template <typename T, typename U>
struct P : pair<T, U> {
  template <typename... Args>
  P(Args... args) : pair<T, U>(args...) {}

  using pair<T, U>::first;
  using pair<T, U>::second;

  P &operator+=(const P &r) {
    first += r.first;
    second += r.second;
    return *this;
  }
  P &operator-=(const P &r) {
    first -= r.first;
    second -= r.second;
    return *this;
  }
  P &operator*=(const P &r) {
    first *= r.first;
    second *= r.second;
    return *this;
  }
  template <typename S>
  P &operator*=(const S &r) {
    first *= r, second *= r;
    return *this;
  }
  P operator+(const P &r) const { return P(*this) += r; }
  P operator-(const P &r) const { return P(*this) -= r; }
  P operator*(const P &r) const { return P(*this) *= r; }
  template <typename S>
  P operator*(const S &r) const {
    return P(*this) *= r;
  }
  P operator-() const { return P{-first, -second}; }
};

using pl = P<ll, ll>;
using pi = P<int, int>;
using vp = V<pl>;

constexpr int inf = 1001001001;
constexpr long long infLL = 4004004004004004004LL;

template <typename T>
int sz(const T &t) {
  return t.size();
}

template <typename T, typename U>
inline bool amin(T &x, U y) {
  return (y < x) ? (x = y, true) : false;
}
template <typename T, typename U>
inline bool amax(T &x, U y) {
  return (x < y) ? (x = y, true) : false;
}

template <typename T>
inline T Max(const vector<T> &v) {
  return *max_element(begin(v), end(v));
}
template <typename T>
inline T Min(const vector<T> &v) {
  return *min_element(begin(v), end(v));
}
template <typename T>
inline long long Sum(const vector<T> &v) {
  return accumulate(begin(v), end(v), 0LL);
}

template <typename T>
int lb(const vector<T> &v, const T &a) {
  return lower_bound(begin(v), end(v), a) - begin(v);
}
template <typename T>
int ub(const vector<T> &v, const T &a) {
  return upper_bound(begin(v), end(v), a) - begin(v);
}

constexpr long long TEN(int n) {
  long long ret = 1, x = 10;
  for (; n; x *= x, n >>= 1) ret *= (n & 1 ? x : 1);
  return ret;
}

template <typename T, typename U>
pair<T, U> mkp(const T &t, const U &u) {
  return make_pair(t, u);
}

template <typename T>
vector<T> mkrui(const vector<T> &v, bool rev = false) {
  vector<T> ret(v.size() + 1);
  if (rev) {
    for (int i = int(v.size()) - 1; i >= 0; i--) ret[i] = v[i] + ret[i + 1];
  } else {
    for (int i = 0; i < int(v.size()); i++) ret[i + 1] = ret[i] + v[i];
  }
  return ret;
};

template <typename T>
vector<T> mkuni(const vector<T> &v) {
  vector<T> ret(v);
  sort(ret.begin(), ret.end());
  ret.erase(unique(ret.begin(), ret.end()), ret.end());
  return ret;
}

template <typename F>
vector<int> mkord(int N, F f) {
  vector<int> ord(N);
  iota(begin(ord), end(ord), 0);
  sort(begin(ord), end(ord), f);
  return ord;
}

template <typename T>
vector<int> mkinv(vector<T> &v) {
  int max_val = *max_element(begin(v), end(v));
  vector<int> inv(max_val + 1, -1);
  for (int i = 0; i < (int)v.size(); i++) inv[v[i]] = i;
  return inv;
}

vector<int> mkiota(int n) {
  vector<int> ret(n);
  iota(begin(ret), end(ret), 0);
  return ret;
}

template <typename T>
T mkrev(const T &v) {
  T w{v};
  reverse(begin(w), end(w));
  return w;
}

template <typename T>
bool nxp(T &v) {
  return next_permutation(begin(v), end(v));
}

// 返り値の型は入力の T に依存
// i 要素目 : [0, a[i])
template <typename T>
vector<vector<T>> product(const vector<T> &a) {
  vector<vector<T>> ret;
  vector<T> v;
  auto dfs = [&](auto rc, int i) -> void {
    if (i == (int)a.size()) {
      ret.push_back(v);
      return;
    }
    for (int j = 0; j < a[i]; j++) v.push_back(j), rc(rc, i + 1), v.pop_back();
  };
  dfs(dfs, 0);
  return ret;
}

// F : function(void(T&)), mod を取る操作
// T : 整数型のときはオーバーフローに注意する
template <typename T>
T Power(T a, long long n, const T &I, const function<void(T &)> &f) {
  T res = I;
  for (; n; f(a = a * a), n >>= 1) {
    if (n & 1) f(res = res * a);
  }
  return res;
}
// T : 整数型のときはオーバーフローに注意する
template <typename T>
T Power(T a, long long n, const T &I = T{1}) {
  return Power(a, n, I, function<void(T &)>{[](T &) -> void {}});
}

template <typename T>
T Rev(const T &v) {
  T res = v;
  reverse(begin(res), end(res));
  return res;
}

template <typename T>
vector<T> Transpose(const vector<T> &v) {
  using U = typename T::value_type;
  if(v.empty()) return {};
  int H = v.size(), W = v[0].size();
  vector res(W, T(H, U{}));
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      res[j][i] = v[i][j];
    }
  }
  return res;
}

template <typename T>
vector<T> Rotate(const vector<T> &v, int clockwise = true) {
  using U = typename T::value_type;
  int H = v.size(), W = v[0].size();
  vector res(W, T(H, U{}));
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (clockwise) {
        res[W - 1 - j][i] = v[i][j];
      } else {
        res[j][H - 1 - i] = v[i][j];
      }
    }
  }
  return res;
}

}  // namespace Nyaan
#line 58 "template/template.hpp"

// bit operation
#line 1 "template/bitop.hpp"
namespace Nyaan {
__attribute__((target("popcnt"))) inline int popcnt(const u64 &a) {
  return __builtin_popcountll(a);
}
inline int lsb(const u64 &a) { return a ? __builtin_ctzll(a) : 64; }
inline int ctz(const u64 &a) { return a ? __builtin_ctzll(a) : 64; }
inline int msb(const u64 &a) { return a ? 63 - __builtin_clzll(a) : -1; }
template <typename T>
inline int gbit(const T &a, int i) {
  return (a >> i) & 1;
}
template <typename T>
inline void sbit(T &a, int i, bool b) {
  if (gbit(a, i) != b) a ^= T(1) << i;
}
constexpr long long PW(int n) { return 1LL << n; }
constexpr long long MSK(int n) { return (1LL << n) - 1; }
}  // namespace Nyaan
#line 61 "template/template.hpp"

// inout
#line 1 "template/inout.hpp"
namespace Nyaan {

template <typename T, typename U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
  os << p.first << " " << p.second;
  return os;
}
template <typename T, typename U>
istream &operator>>(istream &is, pair<T, U> &p) {
  is >> p.first >> p.second;
  return is;
}

template <typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
  int s = (int)v.size();
  for (int i = 0; i < s; i++) os << (i ? " " : "") << v[i];
  return os;
}
template <typename T>
istream &operator>>(istream &is, vector<T> &v) {
  for (auto &x : v) is >> x;
  return is;
}

istream &operator>>(istream &is, __int128_t &x) {
  string S;
  is >> S;
  x = 0;
  int flag = 0;
  for (auto &c : S) {
    if (c == '-') {
      flag = true;
      continue;
    }
    x *= 10;
    x += c - '0';
  }
  if (flag) x = -x;
  return is;
}

istream &operator>>(istream &is, __uint128_t &x) {
  string S;
  is >> S;
  x = 0;
  for (auto &c : S) {
    x *= 10;
    x += c - '0';
  }
  return is;
}

ostream &operator<<(ostream &os, __int128_t x) {
  if (x == 0) return os << 0;
  if (x < 0) os << '-', x = -x;
  string S;
  while (x) S.push_back('0' + x % 10), x /= 10;
  reverse(begin(S), end(S));
  return os << S;
}
ostream &operator<<(ostream &os, __uint128_t x) {
  if (x == 0) return os << 0;
  string S;
  while (x) S.push_back('0' + x % 10), x /= 10;
  reverse(begin(S), end(S));
  return os << S;
}

void in() {}
template <typename T, class... U>
void in(T &t, U &...u) {
  cin >> t;
  in(u...);
}

void out() { cout << "\n"; }
template <typename T, class... U, char sep = ' '>
void out(const T &t, const U &...u) {
  cout << t;
  if (sizeof...(u)) cout << sep;
  out(u...);
}

struct IoSetupNya {
  IoSetupNya() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(15);
    cerr << fixed << setprecision(7);
  }
} iosetupnya;

}  // namespace Nyaan
#line 64 "template/template.hpp"

// debug
#line 1 "template/debug.hpp"
namespace DebugImpl {

template <typename U, typename = void>
struct is_specialize : false_type {};
template <typename U>
struct is_specialize<
    U, typename conditional<false, typename U::iterator, void>::type>
    : true_type {};
template <typename U>
struct is_specialize<
    U, typename conditional<false, decltype(U::first), void>::type>
    : true_type {};
template <typename U>
struct is_specialize<U, enable_if_t<is_integral<U>::value, void>> : true_type {
};

void dump(const char& t) { cerr << t; }

void dump(const string& t) { cerr << t; }

void dump(const bool& t) { cerr << (t ? "true" : "false"); }

void dump(__int128_t t) {
  if (t == 0) cerr << 0;
  if (t < 0) cerr << '-', t = -t;
  string S;
  while (t) S.push_back('0' + t % 10), t /= 10;
  reverse(begin(S), end(S));
  cerr << S;
}

void dump(__uint128_t t) {
  if (t == 0) cerr << 0;
  string S;
  while (t) S.push_back('0' + t % 10), t /= 10;
  reverse(begin(S), end(S));
  cerr << S;
}

template <typename U,
          enable_if_t<!is_specialize<U>::value, nullptr_t> = nullptr>
void dump(const U& t) {
  cerr << t;
}

template <typename T>
void dump(const T& t, enable_if_t<is_integral<T>::value>* = nullptr) {
  string res;
  if (t == Nyaan::inf) res = "inf";
  if constexpr (is_signed<T>::value) {
    if (t == -Nyaan::inf) res = "-inf";
  }
  if constexpr (sizeof(T) == 8) {
    if (t == Nyaan::infLL) res = "inf";
    if constexpr (is_signed<T>::value) {
      if (t == -Nyaan::infLL) res = "-inf";
    }
  }
  if (res.empty()) res = to_string(t);
  cerr << res;
}

template <typename T, typename U>
void dump(const pair<T, U>&);
template <typename T>
void dump(const pair<T*, int>&);

template <typename T>
void dump(const T& t,
          enable_if_t<!is_void<typename T::iterator>::value>* = nullptr) {
  cerr << "[ ";
  for (auto it = t.begin(); it != t.end();) {
    dump(*it);
    cerr << (++it == t.end() ? "" : ", ");
  }
  cerr << " ]";
}

template <typename T, typename U>
void dump(const pair<T, U>& t) {
  cerr << "( ";
  dump(t.first);
  cerr << ", ";
  dump(t.second);
  cerr << " )";
}

template <typename T>
void dump(const pair<T*, int>& t) {
  cerr << "[ ";
  for (int i = 0; i < t.second; i++) {
    dump(t.first[i]);
    cerr << (i == t.second - 1 ? "" : ", ");
  }
  cerr << " ]";
}

void trace() { cerr << endl; }
template <typename Head, typename... Tail>
void trace(Head&& head, Tail&&... tail) {
  cerr << " ";
  dump(head);
  if (sizeof...(tail) != 0) cerr << ",";
  trace(std::forward<Tail>(tail)...);
}

}  // namespace DebugImpl

#ifdef NyaanDebug
#define trc(...)                            \
  do {                                      \
    cerr << "## " << #__VA_ARGS__ << " = "; \
    DebugImpl::trace(__VA_ARGS__);          \
  } while (0)
#else
#define trc(...) (void(0))
#endif

#ifdef NyaanLocal
#define trc2(...)                           \
  do {                                      \
    cerr << "## " << #__VA_ARGS__ << " = "; \
    DebugImpl::trace(__VA_ARGS__);          \
  } while (0)
#else
#define trc2(...) (void(0))
#endif
#line 67 "template/template.hpp"

// macro
#line 1 "template/macro.hpp"
#define each(x, v) for (auto&& x : v)
#define each2(x, y, v) for (auto&& [x, y] : v)
#define all(v) (v).begin(), (v).end()
#define rep(i, N) for (long long i = 0; i < (long long)(N); i++)
#define repr(i, N) for (long long i = (long long)(N)-1; i >= 0; i--)
#define rep1(i, N) for (long long i = 1; i <= (long long)(N); i++)
#define repr1(i, N) for (long long i = (N); (long long)(i) > 0; i--)
#define reg(i, a, b) for (long long i = (a); i < (b); i++)
#define regr(i, a, b) for (long long i = (b)-1; i >= (a); i--)
#define fi first
#define se second
#define ini(...)   \
  int __VA_ARGS__; \
  in(__VA_ARGS__)
#define inl(...)         \
  long long __VA_ARGS__; \
  in(__VA_ARGS__)
#define ins(...)      \
  string __VA_ARGS__; \
  in(__VA_ARGS__)
#define in2(s, t)                           \
  for (int i = 0; i < (int)s.size(); i++) { \
    in(s[i], t[i]);                         \
  }
#define in3(s, t, u)                        \
  for (int i = 0; i < (int)s.size(); i++) { \
    in(s[i], t[i], u[i]);                   \
  }
#define in4(s, t, u, v)                     \
  for (int i = 0; i < (int)s.size(); i++) { \
    in(s[i], t[i], u[i], v[i]);             \
  }
#define die(...)             \
  do {                       \
    Nyaan::out(__VA_ARGS__); \
    return;                  \
  } while (0)
#line 70 "template/template.hpp"

namespace Nyaan {
void solve();
}
int main() { Nyaan::solve(); }
#line 4 "verify/verify-aoj-grl/aoj-grl-5-a-dynamic-rerooting.test.cpp"
//
#line 2 "tree/dynamic-rerooting.hpp"

namespace DynamicRerootingImpl {
template <typename Point, Point (*rake)(const Point &, const Point &)>
struct SplayTreeforDashedEdge {
  struct Node {
    Node *l, *r, *p;
    Point key, sum;

    explicit Node(const Point &_key)
        : l(nullptr), r(nullptr), p(nullptr), key(_key), sum(_key) {}
  };

  SplayTreeforDashedEdge() {}

  using NP = Node *;

  void rotr(NP t) {
    NP x = t->p, y = x->p;
    if ((x->l = t->r)) t->r->p = x;
    t->r = x, x->p = t;
    update(x), update(t);
    if ((t->p = y)) {
      if (y->l == x) y->l = t;
      if (y->r == x) y->r = t;
    }
  }

  void rotl(NP t) {
    NP x = t->p, y = x->p;
    if ((x->r = t->l)) t->l->p = x;
    t->l = x, x->p = t;
    update(x), update(t);
    if ((t->p = y)) {
      if (y->l == x) y->l = t;
      if (y->r == x) y->r = t;
    }
  }

  void update(NP t) {
    t->sum = t->key;
    if (t->l) t->sum = rake(t->sum, t->l->sum);
    if (t->r) t->sum = rake(t->sum, t->r->sum);
  }

  NP get_right(NP t) {
    while (t->r) t = t->r;
    return t;
  }

  NP alloc(const Point &v) {
    auto t = new Node(v);
    update(t);
    return t;
  }

  void splay(NP t) {
    while (t->p) {
      NP q = t->p;
      if (!q->p) {
        if (q->l == t)
          rotr(t);
        else
          rotl(t);
      } else {
        NP r = q->p;
        if (r->l == q) {
          if (q->l == t)
            rotr(q), rotr(t);
          else
            rotl(t), rotr(t);
        } else {
          if (q->r == t)
            rotl(q), rotl(t);
          else
            rotr(t), rotl(t);
        }
      }
    }
  }

  NP insert(NP t, const Point &v) {
    if (not t) {
      t = alloc(v);
      return t;
    } else {
      NP cur = get_right(t), z = alloc(v);
      splay(cur);
      z->p = cur;
      cur->r = z;
      update(cur);
      splay(z);
      return z;
    }
  }

  NP erase(NP t) {
    splay(t);
    NP x = t->l, y = t->r;
    delete t;
    if (not x) {
      t = y;
      if (t) t->p = nullptr;
    } else if (not y) {
      t = x;
      t->p = nullptr;
    } else {
      x->p = nullptr;
      t = get_right(x);
      splay(t);
      t->r = y;
      y->p = t;
      update(t);
    }
    return t;
  }
};

template <typename Path, typename Point, typename Info,
          Path (*vertex)(const Info &),
          Path (*compress)(const Path &, const Path &),
          Point (*rake)(const Point &, const Point &),
          Point (*add_edge)(const Path &),
          Path (*add_vertex)(const Point &, const Info &)>
struct TopTree {
 private:
  struct Node {
    Node *l, *r, *p;
    Info info;
    Path key, sum, mus;
    typename SplayTreeforDashedEdge<Point, rake>::Node *light, *belong;
    bool rev;

    bool is_root() const { return not p or (p->l != this and p->r != this); }

    explicit Node(const Info _info)
        : l(nullptr),
          r(nullptr),
          p(nullptr),
          info(_info),
          light(nullptr),
          belong(nullptr),
          rev(false) {}
  };

 public:
  using NP = Node *;
  SplayTreeforDashedEdge<Point, rake> splay_tree;

 private:
  void toggle(NP t) {
    swap(t->l, t->r);
    swap(t->sum, t->mus);
    t->rev ^= true;
  }

  void rotr(NP t) {
    NP x = t->p, y = x->p;
    push(x), push(t);
    if ((x->l = t->r)) t->r->p = x;
    t->r = x, x->p = t;
    update(x), update(t);
    if ((t->p = y)) {
      if (y->l == x) y->l = t;
      if (y->r == x) y->r = t;
    }
  }

  void rotl(NP t) {
    NP x = t->p, y = x->p;
    push(x), push(t);
    if ((x->r = t->l)) t->l->p = x;
    t->l = x, x->p = t;
    update(x), update(t);
    if ((t->p = y)) {
      if (y->l == x) y->l = t;
      if (y->r == x) y->r = t;
    }
  }

 public:
  TopTree() : splay_tree{} {}

  void push(NP t) {
    if (t->rev) {
      if (t->l) toggle(t->l);
      if (t->r) toggle(t->r);
      t->rev = false;
    }
  }

  void push_rev(NP t) {
    if (t->rev) {
      if (t->l) toggle(t->l);
      if (t->r) toggle(t->r);
      t->rev = false;
    }
  }

  void update(NP t) {
    Path key = t->light ? add_vertex(t->light->sum, t->info) : vertex(t->info);
    Path sum = key, mus = key;
    if (t->l) sum = compress(t->l->sum, sum), mus = compress(mus, t->l->mus);
    if (t->r) sum = compress(sum, t->r->sum), mus = compress(t->r->mus, mus);
    t->key = key, t->sum = sum, t->mus = mus;
  }

  void splay(NP t) {
    push(t);
    {
      NP rot = t;
      while (not rot->is_root()) rot = rot->p;
      t->belong = rot->belong;
      if (t != rot) rot->belong = nullptr;
    }
    while (not t->is_root()) {
      NP q = t->p;
      if (q->is_root()) {
        push_rev(q), push_rev(t);
        if (q->l == t)
          rotr(t);
        else
          rotl(t);
      } else {
        NP r = q->p;
        push_rev(r), push_rev(q), push_rev(t);
        if (r->l == q) {
          if (q->l == t)
            rotr(q), rotr(t);
          else
            rotl(t), rotr(t);
        } else {
          if (q->r == t)
            rotl(q), rotl(t);
          else
            rotr(t), rotl(t);
        }
      }
    }
  }

  NP expose(NP t) {
    NP rp = nullptr;
    for (NP cur = t; cur; cur = cur->p) {
      splay(cur);
      if (cur->r) {
        cur->light = splay_tree.insert(cur->light, add_edge(cur->r->sum));
        cur->r->belong = cur->light;
      }
      cur->r = rp;
      if (cur->r) {
        splay_tree.splay(cur->r->belong);
        push(cur->r);
        cur->light = splay_tree.erase(cur->r->belong);
      }
      update(cur);
      rp = cur;
    }
    splay(t);
    return rp;
  }

  void link(NP child, NP parent) {
    expose(parent);
    expose(child);
    child->p = parent;
    parent->r = child;
    update(parent);
  }

  void cut(NP child) {
    expose(child);
    NP parent = child->l;
    child->l = nullptr;
    parent->p = nullptr;
    update(child);
  }

  void evert(NP t) {
    expose(t);
    toggle(t);
    push(t);
  }

  NP alloc(const Info &info) {
    NP t = new Node(info);
    update(t);
    return t;
  }

  bool is_connected(NP u, NP v) {
    expose(u), expose(v);
    return u == v or u->p;
  }

  NP lca(NP u, NP v) {
    if (not is_connected(u, v)) return nullptr;
    expose(u);
    return expose(v);
  }

  void set_key(NP t, const Info &v) {
    expose(t);
    t->info = v;
    update(t);
  }

  // u を根とする sum
  Path query(NP u) {
    evert(u);
    return u->sum;
  }

  // root を根, u を部分木の根とする sum
  Path query_subtree(NP root, NP u) {
    evert(root);
    expose(u);
    NP l = u->l;
    u->l = nullptr;
    update(u);
    auto ret = u->sum;
    u->l = l;
    update(u);
    return ret;
  }
};

template <typename Path, typename Point, typename Info,
          Path (*vertex)(const Info &),
          Path (*compress)(const Path &, const Path &),
          Point (*rake)(const Point &, const Point &),
          Point (*Add_edge)(const Path &),
          Path (*add_vertex)(const Point &, const Info &)>
struct DynamicRerooting {
  int n;
  TopTree<Path, Point, Info, vertex, compress, rake, Add_edge, add_vertex> tt;
  using NP = typename decltype(tt)::NP;
  vector<NP> vs;

  DynamicRerooting(int _n, const vector<Info> &info) : n(_n), vs(n) {
    for (int i = 0; i < n; i++) vs[i] = tt.alloc(info[i]);
  }
  // u-v 間に辺を追加
  void add_edge(int u, int v) {
    tt.evert(vs[u]);
    tt.link(vs[u], vs[v]);
  }
  // u-v 間の辺を削除
  void del_edge(int u, int v) {
    tt.evert(vs[u]);
    tt.cut(vs[v]);
  }
  // 頂点 u の情報を取得
  Info get_info(int u) { return vs[u]->info; }
  // 頂点 u の情報を設定
  void set_info(int u, const Info &info) { tt.set_key(vs[u], info); }
  // 頂点 u を根とするクエリ
  Path query(int u) { return tt.query(vs[u]); }
  // 頂点 root を根, 頂点 u を部分木の根とするクエリ
  Path query_subtree(int root, int u) {
    return tt.query_subtree(vs[root], vs[u]);
  }
};

}  // namespace DynamicRerootingImpl

using DynamicRerootingImpl::DynamicRerooting;
using DynamicRerootingImpl::TopTree;

/*
struct Path {

};
struct Point {

};
struct Info {

};
Path vertex(const Info &i) {

}
Path compress(const Path &p, const Path &c) {

}
Point rake(const Point &a, const Point &b) {

}
Point add_edge(const Path &a) {

}
Path add_vertex(const Point &a, const Info &i) {

}

using DR = DynamicRerooting<Path, Point, Info, vertex, compress, rake, add_edge,
                            add_vertex>;
*/
#line 6 "verify/verify-aoj-grl/aoj-grl-5-a-dynamic-rerooting.test.cpp"
using namespace Nyaan;

struct HalfPath {
  ll d;
  int u;
  friend HalfPath max(const HalfPath &lhs, const HalfPath &rhs) {
    if (lhs.d != rhs.d) return lhs.d > rhs.d ? lhs : rhs;
    return lhs.u > rhs.u ? lhs : rhs;
  }
};
struct Path {
  ll d;
  int u, v;
  friend Path max(const Path &lhs, const Path &rhs) {
    if (lhs.d != rhs.d) return lhs.d > rhs.d ? lhs : rhs;
    if (lhs.u != rhs.u) return lhs.u > rhs.u ? lhs : rhs;
    return lhs.v > rhs.v ? lhs : rhs;
  }
};
struct L {
  Path dia;
  HalfPath d1, d2;
};
struct H {
  Path dia;
  HalfPath pd, cd;
  ll p_to_c;
  int p, c;
};
using I = pair<ll, int>;
H vertex(const I &xi) {
  auto [x, i] = xi;
  H r;
  r.dia = {x, i, i};
  r.pd = r.cd = {x, i};
  r.p_to_c = x;
  r.p = r.c = i;
  return r;
}
H compress(const H &p, const H &c) {
  H r;
  r.dia = max(max(p.dia, c.dia), {p.cd.d + c.pd.d, p.cd.u, c.pd.u});
  r.pd = max(p.pd, {p.p_to_c + c.pd.d, c.pd.u});
  r.cd = max(c.cd, {c.p_to_c + p.cd.d, p.cd.u});
  r.p_to_c = p.p_to_c + c.p_to_c;
  r.p = p.p, r.c = c.c;
  return r;
}
L rake(const L &a, const L &b) {
  L r;
  r.dia = max(a.dia, b.dia);
  if (a.d1.d > b.d1.d) {
    r.d1 = a.d1;
    r.d2 = max(a.d2, b.d1);
  } else {
    r.d1 = b.d1;
    r.d2 = max(b.d2, a.d1);
  }
  return r;
}
L add_edge(const H &a) {
  L r;
  r.dia = a.dia;
  r.d1 = a.pd;
  r.d2 = {0, -1};
  return r;
}
H add_vertex(const L &a, const I &xi) {
  auto [x, i] = xi;
  H r;
  r.dia = max(a.dia, {a.d1.d + x + a.d2.d, a.d1.u, a.d2.u});
  r.pd = r.cd = {a.d1.d + x, a.d1.u};
  r.p_to_c = x;
  r.p = r.c = i;
  return r;
}

using DD =
    TopTree<H, L, I, vertex, compress, rake, add_edge, add_vertex>;

void q() {
  int N;
  cin >> N;
  DD lct;
  vector<vector<pair<int, int> > > g(N);
  for (int i = 1; i < N; i++) {
    int x, y, z;
    cin >> x >> y >> z;
    g[x].emplace_back(y, z);
    g[y].emplace_back(x, z);
  }
  vector<typename DD::NP> vs(N), es(N);
  auto dfs = [&](auto rec, int idx, int par) -> void {
    vs[idx] = lct.alloc(make_pair(0, idx));
    for (auto &e : g[idx]) {
      if (e.first == par) continue;
      rec(rec, e.first, idx);
      es[e.first] = lct.alloc(make_pair(e.second, -1));
      lct.link(vs[e.first], es[e.first]);
      lct.link(es[e.first], vs[idx]);
    }
  };
  dfs(dfs, 0, -1);

  set<long long> anss;
  for (int i = 0; i < N; i++) {
    long long d = lct.query(vs[i]).dia.d;
    anss.emplace(d);
  }
  if (anss.size() != 1u) exit(1);
  cout << *begin(anss) << endl;
}

void Nyaan::solve() {
  int t = 1;
  // in(t);
  while (t--) q();
}

Nyaan's Library

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verify/verify-aoj-grl/aoj-grl-5-a-dynamic-rerooting.test.cpp

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