proconlib

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:warning: tests/zero_one_bfs/undirected.test.cpp

Depends on

Code

// competitive-verifier: PROBLEM https://atcoder.jp/contests/abc270/tasks/abc270_c
// competitive-verifier: IGNORE

#include <iostream>
#include <ranges>
#include "tools/join.hpp"
#include "tools/zero_one_bfs.hpp"

int main() {
  std::cin.tie(nullptr);
  std::ios_base::sync_with_stdio(false);

  int N, X, Y;
  std::cin >> N >> X >> Y;
  --X, --Y;
  tools::zero_one_bfs<false, int> graph(N);
  for (int i = 0; i < N - 1; ++i) {
    int U, V;
    std::cin >> U >> V;
    --U, --V;
    graph.add_edge(U, V, 1);
  }

  std::cout << tools::join(graph.query<true>(X).vertex_path(Y) | std::views::transform([](const auto v) { return v + 1; }), " ") << '\n';

  return 0;
}

#line 1 "tests/zero_one_bfs/undirected.test.cpp"
// competitive-verifier: PROBLEM https://atcoder.jp/contests/abc270/tasks/abc270_c
// competitive-verifier: IGNORE

#include <iostream>
#include <ranges>
#line 1 "tools/join.hpp"



#line 5 "tools/join.hpp"
#include <sstream>

namespace tools {
  template <::std::ranges::range R, typename T>
  ::std::string join(R&& e, const T& d) {
    ::std::ostringstream ss;
    auto it = ::std::ranges::begin(e);
    const auto end = ::std::ranges::end(e);
    if (it != end) {
      ss << *it;
      for (++it; it != end; ++it) {
        ss << d << *it;
      }
    }
    return ss.str();
  }
}


#line 1 "tools/zero_one_bfs.hpp"



#include <algorithm>
#include <cassert>
#include <deque>
#include <iterator>
#include <limits>
#include <utility>
#include <tuple>
#include <vector>
#line 1 "tools/chmin.hpp"



#include <type_traits>
#line 6 "tools/chmin.hpp"

namespace tools {

  template <typename M, typename N>
  bool chmin(M& lhs, const N& rhs) {
    bool updated;
    if constexpr (::std::is_integral_v<M> && ::std::is_integral_v<N>) {
      updated = ::std::cmp_less(rhs, lhs);
    } else {
      updated = rhs < lhs;
    }
    if (updated) lhs = rhs;
    return updated;
  }
}


#line 1 "tools/shortest_path_tree.hpp"



#line 10 "tools/shortest_path_tree.hpp"

namespace tools {
  template <typename Cost, typename F>
  class shortest_path_tree {
    ::std::vector<Cost> m_dist;
    ::std::vector<int> m_from;
    F m_get_vertex;

  public:
    shortest_path_tree() = default;
    template <::std::ranges::range R1, ::std::ranges::range R2>
    shortest_path_tree(R1&& d, R2&& p, const F& f) : m_get_vertex(f) {
      ::std::ranges::copy(d, ::std::back_inserter(this->m_dist));
      ::std::ranges::copy(p, ::std::back_inserter(this->m_from));
      assert(this->m_dist.size() == this->m_from.size());
      assert(::std::ranges::all_of(this->m_from, [](const auto p_i) { return p_i >= -1; }));
    }

    int size() const {
      return this->m_dist.size();
    }
    const ::std::vector<Cost>& dist() const & {
      return this->m_dist;
    }
    ::std::vector<Cost> dist() && {
      return ::std::move(this->m_dist);
    }
    Cost dist(const int v) const {
      assert(0 <= v && v < this->size());
      return this->m_dist[v];
    }
    int from_vertex(const int v) const {
      assert(0 <= v && v < this->size());
      return this->m_from[v] >= 0 ? this->m_get_vertex(this->m_from[v], v) : -1;
    }
    int from_edge_id(const int v) const {
      assert(0 <= v && v < this->size());
      return this->m_from[v];
    }
    ::std::vector<int> vertex_path(const int v) const {
      assert(0 <= v && v < this->size());
      ::std::vector<int> path;
      for (int u = v; u >= 0; u = this->from_vertex(u)) {
        path.push_back(u);
      }
      ::std::ranges::reverse(path);
      return path;
    }
    ::std::vector<int> edge_id_path(const int v) const {
      assert(0 <= v && v < this->size());
      ::std::vector<int> path;
      for (int u = v; this->m_from[u] >= 0; u = this->from_vertex(u)) {
        path.push_back(this->m_from[u]);
      }
      ::std::ranges::reverse(path);
      return path;
    }
  };

  template <::std::ranges::range R1, ::std::ranges::range R2, typename F>
  shortest_path_tree(R1&&, R2&&, const F&) -> shortest_path_tree<::std::ranges::range_value_t<R1>, F>;
}


#line 14 "tools/zero_one_bfs.hpp"

namespace tools {

  template <bool Directed, typename T>
  class zero_one_bfs {
  public:
    struct edge {
      int from;
      int to;
      T cost;
    };

  private:
    ::std::vector<edge> m_edges;
    ::std::vector<::std::vector<int>> m_graph;

  public:
    zero_one_bfs() = default;
    explicit zero_one_bfs(const int n) : m_graph(n) {
    }

    int size() const {
      return this->m_graph.size();
    }

    int add_edge(int u, int v, const T w) {
      assert(0 <= u && u < this->size());
      assert(0 <= v && v < this->size());
      assert(w == 0 || w == 1);
      if constexpr (!Directed) {
        ::std::tie(u, v) = ::std::minmax({u, v});
      }
      this->m_edges.push_back({u, v, w});
      this->m_graph[u].push_back(this->m_edges.size() - 1);
      if constexpr (!Directed) {
        this->m_graph[v].push_back(this->m_edges.size() - 1);
      }
      return this->m_edges.size() - 1;
    }

    const edge& get_edge(const int k) const & {
      assert(0 <= k && k < ::std::ssize(this->m_edges));
      return this->m_edges[k];
    }
    edge get_edge(const int k) && {
      assert(0 <= k && k < ::std::ssize(this->m_edges));
      return ::std::move(this->m_edges[k]);
    }

    const ::std::vector<edge>& edges() const & {
      return this->m_edges;
    }
    ::std::vector<edge> edges() && {
      return ::std::move(this->m_edges);
    }

    template <bool Restore = false>
    auto query(const int s) const {
      assert(0 <= s && s < this->size());

      ::std::vector<T> dist(this->size(), ::std::numeric_limits<T>::max());
      dist[s] = 0;
      ::std::vector<int> prev(Restore ? this->size() : 0, -1);
      ::std::deque<::std::pair<int, T>> deque;
      deque.emplace_front(s, 0);

      while (!deque.empty()) {
        const auto [here, d] = deque.front();
        deque.pop_front();
        if (dist[here] < d) continue;
        for (const auto edge_id : this->m_graph[here]) {
          const auto& edge = this->m_edges[edge_id];
          const auto next = edge.to ^ (Directed ? 0 : edge.from ^ here);
          if (::tools::chmin(dist[next], dist[here] + edge.cost)) {
            if constexpr (Restore) {
              prev[next] = edge.id;
            }
            if (edge.cost == 0) {
              deque.emplace_front(next, dist[next]);
            } else {
              deque.emplace_back(next, dist[next]);
            }
          }
        }
      }

      if constexpr (Restore) {
        return ::tools::shortest_path_tree(dist, prev, [&](const auto e, const auto v) {
          return this->m_edges[e].from ^ (Directed ? 0 : this->m_edges[e].to ^ v);
        });
      } else {
        return dist;
      }
    }
  };
}


#line 8 "tests/zero_one_bfs/undirected.test.cpp"

int main() {
  std::cin.tie(nullptr);
  std::ios_base::sync_with_stdio(false);

  int N, X, Y;
  std::cin >> N >> X >> Y;
  --X, --Y;
  tools::zero_one_bfs<false, int> graph(N);
  for (int i = 0; i < N - 1; ++i) {
    int U, V;
    std::cin >> U >> V;
    --U, --V;
    graph.add_edge(U, V, 1);
  }

  std::cout << tools::join(graph.query<true>(X).vertex_path(Y) | std::views::transform([](const auto v) { return v + 1; }), " ") << '\n';

  return 0;
}
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