Re: [Boost-users] dijkstra-example.cpp

Subject: Re: [Boost-users] dijkstra-example.cpp
From: Jeremiah Willcock (jewillco_at_[hidden])
Date: 2012-01-27 16:17:57

On Fri, 27 Jan 2012, fergie wrote:

> I’ve been reviewing the dijkstra-example.cpp that is provided as part of
> boost Graph.  I think I understand most of it and have been able to
> demonstrate the application working to my boss.  I have one question about
> the code.  When output the .dot file near the end of the program the results
> are shaded either grey or black.  What is the significance of the black and
> grey lines?

Black lines are edges in the single-source shortest path tree, while gray 
lines are edges that are not in the tree.  Look at 
http://www.cs.cmu.edu/~avrim/451/lectures/lect1008.pdf for exactly what 
the tree represents.

> I’ve looked through the documentation and am also confused
> about the source and the target since we have an iterator going through the
> entire graph.  What defines a source and target vertex?

The graph is directed, so each edge goes from a defined source to a 
defined target.  The arrows in the output file show the directions of the 
edges.

-- Jeremiah Willcock