Iterating over edges of a graph using range-based for

Question

I have a representation of a graph as a std::vector> neighbors, that is, vertices are integers, and for each vertex we keep

Answer 1

An opportunity for a shameless plug! I have a project linq-cpp for bringing .NET LINQ functionality to C++11, and this is a perfect example for where it really shines.

Using it, you could write a function like the following:

TEnumerable> EnumerateEdges(std::vector>& neighbors)
{
    return Enumerable::FromRange(neighbors)
        .SelectManyIndexed([](std::unordered_set& bNodes, int aNode)
        {
            return Enumerable::FromRange(bNodes)
                .Select([=](int bNode){ return std::make_pair(aNode, bNode); });
        });
}

And then use it like this:

EnumerateEdges(neighbors).ForEach([](std::pair edge)
{
    /* your code */
});

Or maybe like this:

auto edges = EnumerateEdges(neighbors).ToVector();