Module org.jgrapht.core
Package org.jgrapht.generate

Class PruferTreeGenerator<V,E>

java.lang.Object
org.jgrapht.generate.PruferTreeGenerator<V,E>
Type Parameters:
V - the graph vertex type
E - the graph edge type
All Implemented Interfaces:
GraphGenerator<V,E,V>
public class PruferTreeGenerator<V,E> extends Object implements GraphGenerator<V,E,V>
Generates a random tree using Prüfer sequences.

A Prüfer sequence of length $n$ is randomly generated and converted into the corresponding tree.

This implementation is inspired by "X. Wang, L. Wang and Y. Wu, "An Optimal Algorithm for Prufer Codes," Journal of Software Engineering and Applications, Vol. 2 No. 2, 2009, pp. 111-115. doi: 10.4236/jsea.2009.22016." and has a running time of $O(n)$.

Author:
Alexandru Valeanu

  • Constructor Details

    • PruferTreeGenerator

      public PruferTreeGenerator(int[] pruferSequence)
      Construct a new PruferTreeGenerator from an input Prüfer sequence. Note that the size of the generated tree will be $l+2$ where $l$ is the length of the input sequence. The Prüfer sequence must contain integers between $0$ and $l+1$ (inclusive). Note: In this case, the same tree will be generated every time.
      Parameters:
      pruferSequence - the input Prüfer sequence
      Throws:
      IllegalArgumentException - if n is ≤ 0
      IllegalArgumentException - if pruferSequence is null
      IllegalArgumentException - if pruferSequence is invalid.

    • PruferTreeGenerator

      public PruferTreeGenerator(int n)
      Construct a new PruferTreeGenerator.
      Parameters:
      n - number of vertices to be generated
      Throws:
      IllegalArgumentException - if n is ≤ 0

    • PruferTreeGenerator

      public PruferTreeGenerator(int n, long seed)
      Construct a new PruferTreeGenerator.
      Parameters:
      n - number of vertices to be generated
      seed - seed for the random number generator
      Throws:
      IllegalArgumentException - if n is ≤ 0

    • PruferTreeGenerator

      public PruferTreeGenerator(int n, Random rng)
      Construct a new PruferTreeGenerator
      Parameters:
      n - number of vertices to be generated
      rng - the random number generator to use
      Throws:
      IllegalArgumentException - if n is ≤ 0
      NullPointerException - if rng is null

  • Method Details