Package groovy.util
Class PermutationGenerator<E>
java.lang.Object
groovy.util.PermutationGenerator<E>
- All Implemented Interfaces:
- java.util.Iterator<java.util.List<E>>
public class PermutationGenerator<E>
extends java.lang.Object
implements java.util.Iterator<java.util.List<E>>
Systematically generate permutations.
 Adapted from Java Code by Michael Gilleland (released with no restrictions) using an algorithm described here:
 Kenneth H. Rosen, Discrete Mathematics and Its Applications, 2nd edition (NY: McGraw-Hill, 1991), pp. 282-284
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Constructor SummaryConstructors Constructor Description PermutationGenerator(java.lang.Iterable<E> items)PermutationGenerator(java.util.Collection<E> items)WARNING: Don't make n too large.
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Method SummaryMethods inherited from class java.lang.Objectclone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, waitMethods inherited from interface java.util.IteratorforEachRemaining
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Constructor Details- 
PermutationGeneratorWARNING: Don't make n too large. Recall that the number of permutations is n! which can be very large, even when n is as small as 20 -- 20! = 2,432,902,008,176,640,000 and 21! is too big to fit into a Java long, which is why we use BigInteger instead.- Parameters:
- items- the items to permute
 
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PermutationGenerator
 
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Method Details- 
resetpublic void reset()
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getTotalpublic java.math.BigInteger getTotal()
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hasNextpublic boolean hasNext()- Specified by:
- hasNextin interface- java.util.Iterator<E>
 
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nextGenerate next permutation (algorithm from Rosen p. 284)- Specified by:
- nextin interface- java.util.Iterator<E>
- Returns:
- the items permuted
 
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removepublic void remove()- Specified by:
- removein interface- java.util.Iterator<E>
 
 
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