グラフ/トポロジカルソート
(test/graph/topological_sort.test.cpp)

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• Last update: 2023-02-25 01:48:23+09:00
• Problem: http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_4_B

Depends on

• 辺 (include/emthrm/graph/edge.hpp)
• トポロジカルソート (topological sort) (include/emthrm/graph/topological_sort.hpp)

Code

/*
 * @title グラフ/トポロジカルソート
 *
 * verification-helper: IGNORE
 * verification-helper: PROBLEM http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_4_B
 */

#include <iostream>
#include <vector>

#include "emthrm/graph/edge.hpp"
#include "emthrm/graph/topological_sort.hpp"

int main() {
  int v, e;
  std::cin >> v >> e;
  std::vector<std::vector<emthrm::Edge<bool>>> graph(v);
  while (e--) {
    int s, t;
    std::cin >> s >> t;
    graph[s].emplace_back(s, t);
  }
  for (const int ans : emthrm::topological_sort(graph)) {
    std::cout << ans << '\n';
  }
  return 0;
}

#line 1 "test/graph/topological_sort.test.cpp"
/*
 * @title グラフ/トポロジカルソート
 *
 * verification-helper: IGNORE
 * verification-helper: PROBLEM http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_4_B
 */

#include <iostream>
#include <vector>

#line 1 "include/emthrm/graph/edge.hpp"
/**
 * @title 辺
 */

#ifndef EMTHRM_GRAPH_EDGE_HPP_
#define EMTHRM_GRAPH_EDGE_HPP_

#include <compare>

namespace emthrm {

template <typename CostType>
struct Edge {
  CostType cost;
  int src, dst;

  explicit Edge(const int src, const int dst, const CostType cost = 0)
      : cost(cost), src(src), dst(dst) {}

  auto operator<=>(const Edge& x) const = default;
};

}  // namespace emthrm

#endif  // EMTHRM_GRAPH_EDGE_HPP_
#line 1 "include/emthrm/graph/topological_sort.hpp"



#include <queue>
#include <ranges>
#include <utility>
#line 8 "include/emthrm/graph/topological_sort.hpp"

#line 1 "include/emthrm/graph/edge.hpp"
/**
 * @title 辺
 */

#ifndef EMTHRM_GRAPH_EDGE_HPP_
#define EMTHRM_GRAPH_EDGE_HPP_

#include <compare>

namespace emthrm {

template <typename CostType>
struct Edge {
  CostType cost;
  int src, dst;

  explicit Edge(const int src, const int dst, const CostType cost = 0)
      : cost(cost), src(src), dst(dst) {}

  auto operator<=>(const Edge& x) const = default;
};

}  // namespace emthrm

#endif  // EMTHRM_GRAPH_EDGE_HPP_
#line 10 "include/emthrm/graph/topological_sort.hpp"

namespace emthrm {

template <typename CostType>
std::vector<int> topological_sort(
    const std::vector<std::vector<Edge<CostType>>>& graph) {
  const int n = graph.size();
  std::vector<int> deg(n, 0);
  for (const int e : graph
                   | std::views::join
                   | std::views::transform(&Edge<CostType>::dst)) {
    ++deg[e];
  }
  std::queue<int> que;
  for (int i = 0; i < n; ++i) {
    if (deg[i] == 0) que.emplace(i);
  }
  std::vector<int> res;
  res.reserve(n);
  while (!que.empty()) {
    const int ver = que.front();
    que.pop();
    res.emplace_back(ver);
    for (const int e : graph[ver]
                     | std::views::transform(&Edge<CostType>::dst)) {
      if (--deg[e] == 0) que.emplace(e);
    }
  }
  return std::cmp_equal(res.size(), n) ? res : std::vector<int>{};
}

}  // namespace emthrm


#line 13 "test/graph/topological_sort.test.cpp"

int main() {
  int v, e;
  std::cin >> v >> e;
  std::vector<std::vector<emthrm::Edge<bool>>> graph(v);
  while (e--) {
    int s, t;
    std::cin >> s >> t;
    graph[s].emplace_back(s, t);
  }
  for (const int ans : emthrm::topological_sort(graph)) {
    std::cout << ans << '\n';
  }
  return 0;
}

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