cc.redberry.core.combinatorics

Class IntCombinationPermutationGenerator

java.lang.Object

cc.redberry.core.combinatorics.IntCombinatorialGenerator

cc.redberry.core.combinatorics.IntCombinationPermutationGenerator

All Implemented Interfaces:

IntCombinatorialPort, OutputPort<int[]>, java.lang.Iterable<int[]>, java.util.Iterator<int[]>

public final class IntCombinationPermutationGenerator
extends IntCombinatorialGenerator
implements IntCombinatorialPort

This class represents an iterator over over all possible unique combinations with permutations (i.e. {0,1} and {1,0} both will appear in the iteration) of k numbers, which can be chosen from the set of n numbers (0,1,2,...,n). The total number of such combinations will be n!/(n-k)!.

For example, for k=2 and n=3, it will produce the following arrays sequence: [0,1], [1,0], [0,2], [2,0], [1,2], [2,1].

The iterator is implemented such that each next combination will be calculated only on the invocation of method next() (no pre-calculation of results).

Note: method next() returns the same reference on each invocation. So, if it is needed not only to obtain the information from next(), but also to save the result, it is necessary to clone the returned array!

Inner implementation of this class is simply uses the combination of IntCombinationsGenerator and IntPermutationsGenerator.

Since:

1.0

See Also:

IntCombinationsGenerator, IntPermutationsGenerator

Nested Class Summary

Nested classes/interfaces inherited from interface cc.redberry.core.utils.OutputPort

OutputPort.PortIterable<T>, OutputPort.PortIterator<T>, OutputPort.Singleton<T>

Constructor Summary

Constructors

Constructor and Description
IntCombinationPermutationGenerator(int n, int k)

Method Summary

Modifier and Type	Method and Description
int[]	getReference() Returns the reference on the current iteration element.
boolean	hasNext()
int[]	next() Calculates and returns the next combination.
void	remove() Throws UnsupportedOperationException.
void	reset() Resets the iteration
int[]	take() Calculates and returns the next combination or null, if no more combinations exist.

Methods inherited from class cc.redberry.core.combinatorics.IntCombinatorialGenerator

iterator

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Methods inherited from interface java.util.Iterator

forEachRemaining

Constructor Detail

IntCombinationPermutationGenerator

public IntCombinationPermutationGenerator(int n,
                                          int k)

Method Detail

take

public int[] take()

Description copied from interface: IntCombinatorialPort

Calculates and returns the next combination or null, if no more combinations exist.

Specified by:

take in interface IntCombinatorialPort

Specified by:

take in interface OutputPort<int[]>

Returns:

the next combination or null, if no more combinations exist

hasNext

public boolean hasNext()

Specified by:

hasNext in interface java.util.Iterator<int[]>

next

public int[] next()

Calculates and returns the next combination.

Specified by:

next in interface java.util.Iterator<int[]>

Returns:

the next combination

remove

public void remove()

Throws UnsupportedOperationException.

Specified by:

remove in interface java.util.Iterator<int[]>

reset

public void reset()

Description copied from class: IntCombinatorialGenerator

Resets the iteration

Specified by:

reset in interface IntCombinatorialPort

Specified by:

reset in class IntCombinatorialGenerator

getReference

public int[] getReference()

Description copied from class: IntCombinatorialGenerator

Returns the reference on the current iteration element.

Specified by:

getReference in interface IntCombinatorialPort

Specified by:

getReference in class IntCombinatorialGenerator

Returns:

the reference on the current iteration element