gov.nasa.jpf.util

Class TotalPermutationGenerator

java.lang.Object

gov.nasa.jpf.util.PermutationGenerator

gov.nasa.jpf.util.TotalPermutationGenerator

public class TotalPermutationGenerator
extends PermutationGenerator

a pull mode generator for permutations that executes in constant space, using Ives' algorithm (F. M. Ives: Permutation enumeration: four new permutation algorithms, Comm. ACM, 19, 2, Feb 1976, pg. 68-72) NOTE - this is mostly here for completeness, since use of full permutations in most cases is prohibitive due to N!

Field Summary

Fields

Modifier and Type	Field and Description
protected int[]	inverse

Fields inherited from class gov.nasa.jpf.util.PermutationGenerator

nElements, nGenerated, nPermutations, permutation

Constructor Summary

Constructors

Constructor and Description
TotalPermutationGenerator(int nElements)

Method Summary

Modifier and Type	Method and Description
protected long	computeNumberOfPermutations()
static long	computeNumberOfPermutations(int nElements)
int[]	next() return the next permutation or throw a NoSuchElementException if there is none.
void	reset()

Methods inherited from class gov.nasa.jpf.util.PermutationGenerator

getNumberOfGeneratedPermutations, getNumberOfPermutations, hasNext, initPermutations, printOn, printOn

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

inverse

protected int[] inverse

Constructor Detail

TotalPermutationGenerator

public TotalPermutationGenerator(int nElements)

Method Detail

reset

public void reset()

Specified by:

reset in class PermutationGenerator

computeNumberOfPermutations

public static long computeNumberOfPermutations(int nElements)

computeNumberOfPermutations

protected long computeNumberOfPermutations()

Specified by:

computeNumberOfPermutations in class PermutationGenerator

next

public int[] next()

Description copied from class: PermutationGenerator

return the next permutation or throw a NoSuchElementException if there is none. NOTE - this does not guarantee to return a different object on each call, i.e. the caller has to clone if the result is stored directly

Specified by:

next in class PermutationGenerator