Recursive Cut and Stitch: Fast All-Pairs Shortest Paths Computation for Subset of Nodes

We present a practical algorithm for computing all pairs shortest paths for subset of nodes on road networks. It provides an important improvement for applications such as traffic analysis, where recomputation of shortest paths is the most expensive step that has to be repeated many times. We propose an algorithm that recursively cuts the graph until pieces are small enough to compute shortest paths fast, and then combines partial shortest path distances bottom-up. Theoretical worst-case running time of our algorithm is slightly slower than Dijkstra, but in practice, our algorithm is significantly faster.