Tree Diameter (SPFA) (verify/graph/tree_diameter_spfa.test.cpp)

View this file on GitHub
Last update: 2025-12-12 22:29:00+01:00
Problem: https://judge.yosupo.jp/problem/tree_diameter

Depends on

Code

// @brief Tree Diameter (SPFA)
#define PROBLEM "https://judge.yosupo.jp/problem/tree_diameter"
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2")
#include <iostream>
//#include "blazingio/blazingio.min.hpp"
#include "cp-algo/graph/shortest_path.hpp"
#include <bits/stdc++.h>

using namespace std;
using namespace cp_algo::graph;

template<weighted_undirected_graph_type graph>
std::tuple<int64_t, node_index, cp_algo::big_vector<edge_index>> tree_diameter(graph const& g) {
    auto [d1, _] = spfa(g, 0);
    node_index s = 0;
    for(auto v: g.nodes()) {
        if (d1[v] > d1[s]) {
            s = v;
        }
    }
    auto [d2, pre] = spfa(g, s);
    node_index t = 0;
    for(auto v: g.nodes()) {
        if (d2[v] > d2[t]) {
            t = v;
        }
    }
    return {d2[t], s, recover_path(g, pre, s, t)};
}

void solve() {
    int n;
    cin >> n;
    weighted_graph g(n);
    g.read_edges(n - 1);
    auto [d, v, path] = tree_diameter(g);
    cout << d << ' ' << size(path) + 1 << '\n';
    cout << v;
    for(auto e: path) {
        v = g.edge(e).traverse(v);
        cout << ' ' << v;
    }
    cout << "\n";
}

signed main() {
    //freopen("input.txt", "r", stdin);
    ios::sync_with_stdio(0);
    cin.tie(0);
    int t = 1;
    //cin >> t;
    while(t--) {
        solve();
    }
}

Traceback (most recent call last):
  File "/home/runner/.local/lib/python3.12/site-packages/competitive_verifier/oj_resolve/resolver.py", line 181, in resolve
    bundled_code = language.bundle(path, basedir=basedir)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/runner/.local/lib/python3.12/site-packages/competitive_verifier/oj/verify/languages/cplusplus.py", line 252, in bundle
    bundler.update(path)
  File "/home/runner/.local/lib/python3.12/site-packages/competitive_verifier/oj/verify/languages/cplusplus_bundle.py", line 327, in update
    assert len(lines) == len(uncommented_lines)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError

Test cases

Env	Name	Status	Elapsed	Memory
g++	example_00	AC	5 ms	4 MB
g++	hack_00	AC	4 ms	4 MB
g++	line_00	AC	189 ms	45 MB
g++	max_random_00	AC	231 ms	41 MB
g++	max_random_01	AC	252 ms	42 MB
g++	random_00	AC	178 ms	35 MB
g++	random_01	AC	199 ms	39 MB
g++	random_02	AC	27 ms	7 MB
g++	random_03	AC	182 ms	37 MB
g++	random_04	AC	118 ms	28 MB
g++	small_random_00	AC	5 ms	4 MB
g++	small_random_01	AC	4 ms	4 MB
g++	small_random_02	AC	4 ms	4 MB
g++	small_random_03	AC	4 ms	4 MB
g++	small_random_04	AC	4 ms	4 MB
g++	uni_00	AC	142 ms	43 MB