Add a few more BFS-based algorithms #51
                
     Merged
            
            
          
  Add this suggestion to a batch that can be applied as a single commit.
  This suggestion is invalid because no changes were made to the code.
  Suggestions cannot be applied while the pull request is closed.
  Suggestions cannot be applied while viewing a subset of changes.
  Only one suggestion per line can be applied in a batch.
  Add this suggestion to a batch that can be applied as a single commit.
  Applying suggestions on deleted lines is not supported.
  You must change the existing code in this line in order to create a valid suggestion.
  Outdated suggestions cannot be applied.
  This suggestion has been applied or marked resolved.
  Suggestions cannot be applied from pending reviews.
  Suggestions cannot be applied on multi-line comments.
  Suggestions cannot be applied while the pull request is queued to merge.
  Suggestion cannot be applied right now. Please check back later.
  
    
  
    
BFS is a workhorse! There are still many BFS-based algorithms still to do.
My main TODO is to benchmark these to give them a proper shakedown. I like to shake down most algorithms we add. Also, I wonder whether we should use
A.TorATin a couple places. I also wonder if we can come up with a heuristic to detect negative cycles.It may be nice to know whether directed graphs are structurally symmetric. If we knew this, we could improve
is_weakly_connectedand other algorithms.Also, there may be a couple NetworkX bugs to fix or behaviors to match.
Implemented:
is_connectedis_weakly_connectednode_connected_componentall_pairs_shortest_path_lengthnegative_edge_cyclesingle_source_shortest_path_lengthsingle_target_shortest_path_lengthbfs_layersdescendants_at_distance