All simple cycles algorithm

[emperorz]

Depends on SCC algorithm (see issue 38).

Useful for AML/fraud ring detection, feedback mechanism finding.

I suggest Johnson's algorithm, though there is a more general version, but it is behind a paywall (grrr).

Neo4j doesn't seem to do this (no idea why).

Description here: https://www.cs.tufts.edu/comp/150GA/homeworks/hw1/Johnson%2075.PDF

Example code here, it isn't particularly great, but it probably works: https://github.com/mission-peace/interview/blob/master/src/com/interview/graph/AllCyclesInDirectedGraphJohnson.java

There are distributed cycle detection algo's too, but they look tricky. Here's one: https://www.researchgate.net/publication/283642998_Distributed_cycle_detection_in_large-scale_sparse_graphs

Interestingly, we can work backwards from this to strongly connected components.