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josch
e666dad85a

9 years ago  

de/normalisiert/utils/graphs  9 years ago  
Makefile  10 years ago  
README.md  9 years ago 
README.md
Finding all the elementary circuits of a directed graph
Algorithm by D. B. Johnson
Finding all the elementary circuits of a directed graph.
D. B. Johnson, SIAM Journal on Computing 4, no. 1, 7784, 1975.
http://dx.doi.org/10.1137/0204007
Usage
make
echo "0 1\n0 2\n1 0\n1 3\n2 0\n3 0\n3 1\n3 2"  java de.normalisiert.utils.graphs.TestCycles 4
First argument is the number of vertices. Ordered pairs of space separated vertices are given via standard input and make up the directed edges of the graph.
DOT file input
For simplicity, there is no DOT file parser included but the following allows to create a suitable argument string and standard input for simple DOT graphs.
Given a DOT file of a simple (no labels, colors, styles, only pairs of vertices...) directed graph, the following lines generate the number of vertices as well as the edge list expected on standard input.
sed n e '/^\s*[09]\+;$/p' graph.dot  wc l
sed n e 's/^\s*\([09]\) > \([09]\);$/\1 \2/p' graph.dot
The above lines work on DOT files like the following:
digraph G {
0;
1;
2;
0 > 1;
0 > 2;
1 > 0;
2 > 0;
2 > 1;
}
They would produce the following output:
3
0 1
0 2
1 0
2 0
2 1