Dijkstra's algorithm is a graph-based technique for finding the globally shortest path between a starting node and a target node in a non-negative weighted Directed Acyclic Graph (DAG). It is a DAG in that edges are one way and there are no cycles in the graph; it is weighted in that each traversal of the graph has a certain cost. It is used often in graph-based applications such as social, network routing, and logistics supply modeling. In its simplest form, the algorithm performs in O(v2) where |v| is the number of vertices in the graph.
Details of the algorithm may be found here:
Add this line to your application's Gemfile:
gem 'dijkstra'
And then execute:
$ bundle
Or install it yourself as:
$ gem install dijkstra
Use the dijkstra command and pass it a graph file, a starting node, and an ending node.
$ dijkstra my_graph.txt A G
Shortest path is [A,B,E,G] with total cost 6
A graph file is a txt file containing lines and weights. A line consists of two nodes.
[A,B,1]
[B,C,3]
[C,D,1]
[D,F,3]
[E,G,3]
[F,G,1]
[A,C,2]
[B,D,3]
[B,E,2]
[D,E,3]
This file must be a Direct Acyclic Graph (DAG):
- Lines are one way
- Lines are always weighted
- There are no cycles
- Fork it ( http://github.com/jkamenik/dijkstra/fork )
- Create your feature branch (
git checkout -b my-new-feature) - Commit your changes (
git commit -am 'Add some feature') - Push to the branch (
git push origin my-new-feature) - Create new Pull Request