Bellman-Ford algorithm

struct edge {};

// Detects negative cycles in a weighted graph
bool Bellman_Ford(int src, std::vector<std::vector<edge>>& edges)
{
    std::vector<int> distance(edges.size(), 0x3f3f3f3f);
    distance[src] = 0;

    for (int i = 0; i < edges.size(); i++)
        for (int from = 0; from < size(); from++)
            if (distance[from] != 0x3f3f3f3f)
                for (edge& e : edges[from])
                    distance[e.to] = std::min(distance[e.to], e.weight + distance[from]);

    for (int from = 0; from < edges.size(); from++)
        if (distance[from] != 0x3f3f3f3f)
            for (edge& e : edges[from])
                if (distance[from] + e.weight < distance[e.to])
                    return true;

    return false;
}