org.jgrapht.experimental.permutation

Class IntegerPermutationIter

java.lang.Object

org.jgrapht.experimental.permutation.IntegerPermutationIter

All Implemented Interfaces:

Iterator, ArrayPermutationsIter

public class IntegerPermutationIter
extends Object
implements Iterator, ArrayPermutationsIter

Iterates through permutations of N elements.

1. use getNext() to get the next permutation order, for example(N=4): perm0=[1,2,3,4] perm1=[1,2,4,3] perm2=[1,3,2,4] .
2. use hasNext() or verify by counter<getTotalNumberOfPermutations () that you do not overflow the max number. RunTimeException will be thrown if you do. Getting the next permutation is done in O(N) Note: This class is not thread safe.

Since:

May 20, 2005

Author:

Assaf

Constructor Summary

Constructors

Constructor and Description
IntegerPermutationIter(int N) Creates an array of size N with elements 1,2,...,n-1 Useful for describing regular permutations.
IntegerPermutationIter(int[] array) Uses a predefined array (sorted), for example: [3,1,1,2,1]-->[1,1,1,2,3]; note that there are much less than 5! premutations here, because of the repetitive 1s.

Method Summary

Methods

Modifier and Type	Method and Description
int[]	getCurrent()
int[]	getNext() Facade.
boolean	hasNext() Efficiency: O(N) implementation, try to take the next!
boolean	hasNextPermutaions()
Object	next()
int[]	nextPermutation()
void	remove() UNIMPLEMENTED.
String	toString(int[] array) Utility method to convert the array into a string examples: [] [0] [0,1][1,0]

Methods inherited from class java.lang.Object

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

Constructor Detail

IntegerPermutationIter

public IntegerPermutationIter(int N)

Creates an array of size N with elements 1,2,...,n-1 Useful for describing regular permutations. See IntegerPermutationIter(int[] array) for the other kind of permutations; efficency of initiation is O(N)

Parameters:

N -

IntegerPermutationIter

public IntegerPermutationIter(int[] array)

Uses a predefined array (sorted), for example: [3,1,1,2,1]-->[1,1,1,2,3]; note that there are much less than 5! premutations here, because of the repetitive 1s.

Parameters:

array - creates a copy of it (so sort / later changes will not matter)

Method Detail

hasNext

public boolean hasNext()

Efficiency: O(N) implementation, try to take the next!

Specified by:

hasNext in interface Iterator

next

public Object next()

Specified by:

next in interface Iterator

getNext

public int[] getNext()

Facade. use it with getNext. efficency: O(N)

Returns:

a new Array with the permutatation order. for example: perm0=[1,2,3,4] perm1=[1,2,4,3] perm2=[1,3,2,4]

getCurrent

public int[] getCurrent()

toString

public String toString(int[] array)

Utility method to convert the array into a string examples: [] [0] [0,1][1,0]

Parameters:

array -

remove

public void remove()

UNIMPLEMENTED. always throws new UnsupportedOperationException

Specified by:

remove in interface Iterator

See Also:

Iterator.remove()

nextPermutation

public int[] nextPermutation()

Specified by:

nextPermutation in interface ArrayPermutationsIter

hasNextPermutaions

public boolean hasNextPermutaions()

Specified by:

hasNextPermutaions in interface ArrayPermutationsIter