Graph implementation C++

Question

I was wondering about a quick to write implementation of a graph in c++. I need the data structure to be easy to manipulate and use graph algorithms(such as BFS,DFS, Kruskal

Answer 1

This question is ancient but for some reason I can't seem to get it out of my mind.

While all of the solutions do provide an implementation of graphs, they are also all very verbose. They are simply not elegant.

Instead of inventing your own graph class all you really need is a way to tell that one point is connected to another -- for that, std::map and std::unordered_map work perfectly fine. Simply, define a graph as a map between nodes and lists of edges. If you don't need extra data on the edge, a list of end nodes will do just fine.

Thus a succinct graph in C++, could be implemented like so:

using graph = std::map>;

Or, if you need additional data,

struct edge {
    int nodes[2];
    float cost; // add more if you need it
};

using graph = std::map>;

Now your graph structure will plug nicely into the rest of the language and you don't have to remember any new clunky interface -- the old clunky interface will do just fine.

No benchmarks, but I have a feeling this will also outperform the other suggestions here.

NB: the ints are not indices -- they are identifiers.