What would be a good algorithm for a circular reference check in this case?

Question

Given you have the following class (bad C#, but you get the drift):

public abstract class AmICircular
{
  // assume Children is never null
  private List

        

Answer 1

The iterative solution is to define a set R (reachable) and CR (children of Reachable).

You start of with R = {this} and CR = {this.children}.

In each step, you check if CR contains this (or target, depending on your exact goal). If not, you add CR to R and set CR to the children of CR, and remove the elements of R from CR.

If CR becomes empty, R is the complete set of elements reachable from this.