dijkstra reads a stream of graphs and for each computes the distance of every
sourcenode. Edge length is given in the
len attribute, and the default is 1. The
dist attribute of every node is set to its distance from
sourcenode. If the -p flag is used, the
prev attribute of each node reachable from
sourcenode is set to the name of the previous node on a shortest path.
The graph attribute
maxdist is set to the maximum
dist of all nodes in the graph.
If the -d flag is used, the graph is treated as directed and
only forward edges are used.
By default, if the graph is disconnected, the
dist attribute of nodes unreachable from
sourcenode are left untouched, and
maxdist is set to the maximum of any previous value and the largest
distance recorded in this run. On the other hand, if
the -a flag is used, the
dist attribute of an unreachable node is assigned a very large value,
maxdist records the maximum distance found in the component containing
Any number of
sourcenode file pairs may be given.
If the last
file is missing, stdin is used.
All output is written to stdout.
In a typical application,
maxdist can drive a downstream calculation of color or some other attribute.