#include "bellman_ford.h"

#include <stdexcept>

void BellmanFord::Graph::BellmanFordAlgorithm(Vertex& source)

{

for (int i = 0; i < static_cast<int>(vertices.size()) - 1; ++i)

{

for (auto& [u, v] : adjacency_list)

{

// Relaxation

const auto weight_uv = weight_list.at(std::make_pair(u->id, v->id));

if (v->distance > (u->distance + weight_uv))

{

v->distance = u->distance + weight_uv;

v->predecessor = u;

}

}

}

for (auto& [u, v] : adjacency_list)

{

if (v->distance > (u->distance + weight_list.at(std::make_pair(u->id, v->id))))

{

throw std::runtime_error("Graph has a negative cycle");

}

}

}

void BellmanFord::Graph::AddVertex(Vertex& v)

{

vertices.push_back(&v);

}

void BellmanFord::Graph::AddEdge(Vertex& u, Vertex& v, int weight)

{

adjacency_list.emplace_back(&u, &v);

u.neighbors.insert(&v);

weight_list.insert(std::make_pair(std::make_pair(u.id, v.id), weight));

}