Graph/dijkstra.hpp

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Last update: 2020-11-05 12:15:41+09:00
Include: #include "Graph/dijkstra.hpp"

Depends on

Verified with

Verify/dijkstra.test.cpp

Code

#pragma once

#include "../Tools/heap_alias.hpp"
#include "graph.hpp"

template <class Cost>
std::vector<Cost> dijkstra(const Graph<Cost>& graph, int s) {
    std::vector<Cost> dist(graph.size(), -1);
    dist[s] = 0;
    MinHeap<std::pair<Cost, int>> que;
    que.emplace(0, s);

    while (!que.empty()) {
        auto [d, v] = que.top();
        que.pop();
        if (d > dist[v]) continue;

        for (const auto& e : graph[v]) {
            if (dist[e.dst] != -1 &&
                dist[e.dst] <= dist[v] + e.cost) continue;
            dist[e.dst] = dist[v] + e.cost;
            que.emplace(dist[e.dst], e.dst);
        }
    }

    return dist;
}

#line 2 "Graph/dijkstra.hpp"

#line 2 "Tools/heap_alias.hpp"

#include <queue>

template <class T>
using MaxHeap = std::priority_queue<T>;
template <class T>
using MinHeap = std::priority_queue<T, std::vector<T>, std::greater<T>>;
#line 2 "Graph/graph.hpp"

#include <vector>

template <class Cost = int>
struct Edge {
    int src, dst;
    Cost cost;

    Edge() = default;
    Edge(int src, int dst, Cost cost = 1)
        : src(src), dst(dst), cost(cost){};

    bool operator<(const Edge<Cost>& e) const { return cost < e.cost; }
    bool operator>(const Edge<Cost>& e) const { return cost > e.cost; }
};

template <class Cost = int>
struct Graph : public std::vector<std::vector<Edge<Cost>>> {
    using std::vector<std::vector<Edge<Cost>>>::vector;

    void span(bool direct, int src, int dst, Cost cost = 1) {
        (*this)[src].emplace_back(src, dst, cost);
        if (!direct) (*this)[dst].emplace_back(dst, src, cost);
    }
};
#line 5 "Graph/dijkstra.hpp"

template <class Cost>
std::vector<Cost> dijkstra(const Graph<Cost>& graph, int s) {
    std::vector<Cost> dist(graph.size(), -1);
    dist[s] = 0;
    MinHeap<std::pair<Cost, int>> que;
    que.emplace(0, s);

    while (!que.empty()) {
        auto [d, v] = que.top();
        que.pop();
        if (d > dist[v]) continue;

        for (const auto& e : graph[v]) {
            if (dist[e.dst] != -1 &&
                dist[e.dst] <= dist[v] + e.cost) continue;
            dist[e.dst] = dist[v] + e.cost;
            que.emplace(dist[e.dst], e.dst);
        }
    }

    return dist;
}