test/verify/yosupo-tree-diameter.test.cpp

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• Last update: 2026-08-10 11:04:56+00:00
• Problem: https://judge.yosupo.jp/problem/tree_diameter

Depends on

• Graph Template (グラフテンプレート) (graph/graph-template.hpp)
• Tree Diameter (木の直径) (graph/tree/tree-diameter.hpp)

Code

// clang-format off
// competitive-verifier: PROBLEM https://judge.yosupo.jp/problem/tree_diameter
// clang-format on

#include <iostream>

#include "../../graph/tree/tree-diameter.hpp"

using namespace std;

int main() {
  int N;
  cin >> N;
  TreeDiameter<long long> g(N);
  g.read(N - 1, 0, true);
  cout << g.build() << " ";
  cout << g.path.size() + 1 << "\n";
  cout << g.path[0].from;
  for (auto& edge : g.path) cout << " " << edge.to;
  cout << "\n";
}

#line 1 "test/verify/yosupo-tree-diameter.test.cpp"
// clang-format off
// competitive-verifier: PROBLEM https://judge.yosupo.jp/problem/tree_diameter
// clang-format on

#include <iostream>

#line 2 "graph/tree/tree-diameter.hpp"

#include <utility>
#include <vector>

#line 2 "graph/graph-template.hpp"

#include <cstddef>
#line 6 "graph/graph-template.hpp"

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 {
  std::vector<std::vector<Edge<T> > > g;
  int es;

  Graph() = default;

  explicit Graph(int n) : g(n), es(0) {}

  std::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;
      std::cin >> a >> b;
      a += padding;
      b += padding;
      T c = T(1);
      if (weighted) std::cin >> c;
      if (directed)
        add_directed_edge(a, b, c);
      else
        add_edge(a, b, c);
    }
  }

  inline std::vector<Edge<T> >& operator[](const int& k) { return g[k]; }

  inline const std::vector<Edge<T> >& operator[](const int& k) const {
    return g[k];
  }
};

template <typename T = int>
using Edges = std::vector<Edge<T> >;
#line 7 "graph/tree/tree-diameter.hpp"

/**
 * @brief Tree-Diameter(木の直径)
 *
 */
template <typename T = int>
struct TreeDiameter : Graph<T> {
 public:
  using Graph<T>::Graph;
  using Graph<T>::g;
  std::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:
  std::vector<int> to;

  std::pair<T, int> dfs(int idx, int par) {
    std::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 8 "test/verify/yosupo-tree-diameter.test.cpp"

using namespace std;

int main() {
  int N;
  cin >> N;
  TreeDiameter<long long> g(N);
  g.read(N - 1, 0, true);
  cout << g.build() << " ";
  cout << g.path.size() + 1 << "\n";
  cout << g.path[0].from;
  for (auto& edge : g.path) cout << " " << edge.to;
  cout << "\n";
}

Test cases

Env	Name	Status	Elapsed	Memory
g++	example_00	AC	2 ms	4 MB
g++	hack_00	AC	2 ms	4 MB
g++	line_00	AC	617 ms	84 MB
g++	max_random_00	AC	536 ms	50 MB
g++	max_random_01	AC	543 ms	49 MB
g++	random_00	AC	394 ms	39 MB
g++	random_01	AC	479 ms	46 MB
g++	random_02	AC	50 ms	8 MB
g++	random_03	AC	461 ms	43 MB
g++	random_04	AC	261 ms	29 MB
g++	small_random_00	AC	2 ms	4 MB
g++	small_random_01	AC	2 ms	4 MB
g++	small_random_02	AC	2 ms	4 MB
g++	small_random_03	AC	2 ms	4 MB
g++	small_random_04	AC	2 ms	4 MB
g++	uni_00	AC	381 ms	44 MB
clang++	example_00	AC	2 ms	4 MB
clang++	hack_00	AC	2 ms	4 MB
clang++	line_00	AC	700 ms	102 MB
clang++	max_random_00	AC	605 ms	50 MB
clang++	max_random_01	AC	595 ms	49 MB
clang++	random_00	AC	401 ms	39 MB
clang++	random_01	AC	512 ms	46 MB
clang++	random_02	AC	47 ms	8 MB
clang++	random_03	AC	461 ms	43 MB
clang++	random_04	AC	270 ms	29 MB
clang++	small_random_00	AC	2 ms	4 MB
clang++	small_random_01	AC	2 ms	4 MB
clang++	small_random_02	AC	2 ms	4 MB
clang++	small_random_03	AC	2 ms	4 MB
clang++	small_random_04	AC	2 ms	4 MB
clang++	uni_00	AC	404 ms	44 MB

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