public class PermutationGenerator<E> extends Object implements Iterator
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
Constructor and description |
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PermutationGenerator
(Collection<E> items) WARNING: Don't make n too large. |
PermutationGenerator
(Iterable<E> items) |
WARNING: 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.
items
- the items to permuteGenerate next permutation (algorithm from Rosen p. 284)
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