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(graph/topological-sort.hpp)

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• Last update: 2023-11-04 18:06:00+09:00
• Include: #include "graph/topological-sort.hpp"

Depends on

• グラフ構造体 (graph/graph_template.hpp)

Code

#pragma once

#include "graph_template.hpp"

template<typename Cost = int>
std::vector<int> topological_sort(const Graph<Cost>& G) {
    int N = (int)G.size();
    std::vector<int> indeg(N, 0);
    for(int i = 0; i < N; i++) {
        for(const auto& e : G[i]) {
            indeg[e.to]++;
        }
    }
    std::vector<int> st, ret;
    for(int i = 0; i < N; i++) {
        if(indeg[i] == 0) st.push_back(i);
    }
    while(!st.empty()) {
        int u = st.back();
        st.pop_back();
        ret.push_back(u);
        for(const auto& e : G[u]) {
            indeg[e.to]--;
            if(indeg[e.to] == 0) st.push_back(e.to);
        }
    }
    return ret;
}

#line 2 "graph/topological-sort.hpp"

#line 2 "graph/graph_template.hpp"

#include <cassert>
#include <vector>

template <typename Cost = int> struct Edge {
    int from, to;
    Cost cost;
    int id;
    Edge() = default;
    explicit Edge(int from, int to, Cost cost = 1, int id = -1)
        : from(from), to(to), cost(cost), id(id) {}
    operator int() const { return to; }
};

template <typename Cost = int> class Graph {
  public:
    Graph() = default;
    explicit Graph(int N) : N(N), M(0), G(N) {}

    inline void add_directed_edge(int from, int to, Cost cost = 1) {
        assert(0 <= from && from < N);
        assert(0 <= to && to < N);
        G[from].emplace_back(from, to, cost, M++);
    }

    inline void add_undirected_edge(int from, int to, Cost cost = 1) {
        assert(0 <= from && from < N);
        assert(0 <= to && to < N);
        G[from].emplace_back(from, to, cost, M);
        G[to].emplace_back(to, from, cost, M++);
    }

    inline size_t size() const { return G.size(); }
    inline std::vector<Edge<Cost>> &operator[](const int &i) { return G[i]; }
    inline const std::vector<Edge<Cost>> &operator[](const int &i) const {
        return G[i];
    }

  protected:
    int N, M;
    std::vector<std::vector<Edge<Cost>>> G;
};

template <class Cost = int> using Edges = std::vector<Edge<Cost>>;
#line 4 "graph/topological-sort.hpp"

template<typename Cost = int>
std::vector<int> topological_sort(const Graph<Cost>& G) {
    int N = (int)G.size();
    std::vector<int> indeg(N, 0);
    for(int i = 0; i < N; i++) {
        for(const auto& e : G[i]) {
            indeg[e.to]++;
        }
    }
    std::vector<int> st, ret;
    for(int i = 0; i < N; i++) {
        if(indeg[i] == 0) st.push_back(i);
    }
    while(!st.empty()) {
        int u = st.back();
        st.pop_back();
        ret.push_back(u);
        for(const auto& e : G[u]) {
            indeg[e.to]--;
            if(indeg[e.to] == 0) st.push_back(e.to);
        }
    }
    return ret;
}

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