Python: How to find if a path exists between 2 nodes in a graph?

Question

I am using networkx package of Python.

Answer 1

Using a disjoint set data structure:

Create a singleton set for every vertex in the graph, then union the sets containing each of the pair of vertices for every edge in the graph.

Finally, you know a path exists between two vertices if they are in the same set.

See the wikipedia page on the disjoint set data structure.

This is much more efficient than using a path finding algorithm.