I'm going over a lecture recording, in it my professor mentions using Dijkstra's algorithm (or a modified version of it) to find multiple-source to single source shortest paths, e.g. finding the closest hospital out of three hospitals to an accident site.
I have no visuals to see what he is doing on the blackboard, but he describes creating a new 'virtual node' that has a node degree equal to the number of sources, with each edge linking to each intended source, and the cost of this node's edges are 0. I guess the process is that the new virtual node becomes the source, and as each of its edges connect to a real sources for zero cost, it would be computing shortest paths from each source in the most efficient manner.
Is this correct?