Disk-based BFS

An implementation of disk-based breadth first search, using a version of the algorithm described in Richard Korf's paper Minimizing Disk I/O in Two-Bit Breadth-First Search modified to only require one bit per state.

lib.rs:

Breadth-first search using hard drive space for storing intermediate data.

The implementation is efficient, generic, parallel, and can use multiple hard drives. The algorithm is based on the paper Minimizing Disk I/O in Two-Bit Breadth-First Search of Richard Korf, with various improvements. It is suitable for very large implicit graphs (~10^13 nodes), e.g. the 15 puzzle graph.