The above is actually correct, I did not understand what a strongly connected component was. I was expecting the function to return an empty List of strongly connected components, yet it was returning a list of single nodes. I believe the above is working. Feel free to use if you need it!
I cooked up a C program that does this. The key is to ‘rank’ the nodes, and only draw edges from lower ranked nodes to higher ranked ones. The program I wrote prints in the DOT language. Here is the code itself, with comments explaining what it means: #include <stdio.h> #include <stdlib.h> #include <time.h> #define … Read more
You are part of the way there, but you have made a few mistakes. text-anchor=”center” is wrong. It should be text-anchor=”middle”. In addition, you should add startOffset=”50%” to the <textPath> element to specify that the text should be centred on the half-way point of the path. Finally you need to fix the path itself. You … Read more
I would suggest using Floyd’s Cycle-Finding Algorithm aka The Tortoise and the Hare Algorithm. It has O(n) complexity and I think it fits your requirements. Example code: function boolean hasLoop(Node startNode){ Node slowNode = Node fastNode1 = Node fastNode2 = startNode; while (slowNode && fastNode1 = fastNode2.next() && fastNode2 = fastNode1.next()){ if (slowNode == fastNode1 … Read more
iter.next() was removed in python 3. Use next(iter) instead. So in your example change itertools.cycle().next() to next(itertools.cycle()) There is a good example here along with various other porting to python 3 tips. It also compares various other next() idioms in python 2.x vs python 3.x
Jackson 2.0 does support full cyclic object references. See “Jackson 2.0 released” (section ‘Handle Any Object Graphs, even Cyclic ones!’) for an example. Basically, you will need to use new @JsonIdentityInfo for types that require id/idref style handling. In your case this would be both Parent and Child types (if one extends the other, just … Read more
Answering my question: The graph has a cycle if and only if there exists a back edge. A back edge is an edge that is from a node to itself (selfloop) or one of its ancestor in the tree produced by DFS forming a cycle. Both approaches above actually mean the same. However, this method … Read more
Consider throw/catch. Normally the outside loop in the below code will run five times, but with throw you can change it to whatever you like, breaking it in the process. Consider this perfectly valid ruby code: catch (:done) do 5.times { |i| 5.times { |j| puts “#{i} #{j}” throw :done if i + j > … Read more
From a correctness perspective, there is no reason that you need to use the number two. Any choice of step size will work (except for one, of course). However, choosing a step of size two maximizes efficiency. To see this, let’s take a look at why Floyd’s algorithm works in the first place. The idea … Read more
For an undirected graph the standard approach is to look for a so called cycle base : a set of simple cycles from which one can generate through combinations all other cycles. These are not necessarily all simple cycles in the graph. Consider for example the following graph: A / \ B —– C \ … Read more