| [section:prev_permutation prev_permutation] |
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| [heading Prototype] |
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| `` |
| template<class BidirectionalRange> |
| bool prev_permutation(BidirectionalRange& rng); |
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| template<class BidirectionalRange> |
| bool prev_permutation(const BidirectionalRange& rng); |
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| template<class BidirectionalRange, class Compare> |
| bool prev_permutation(BidirectionalRange& rng, Compare pred); |
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| template<class BidirectionalRange, class Compare> |
| bool prev_permutation(const BidirectionalRange& rng, Compare pred); |
| `` |
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| [heading Description] |
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| `prev_permutation` transforms the range of elements `rng` into the lexicographically next smaller permutation of the elements if such a permutation exists. If one does not exist then the range is transformed into the lexicographically largest permutation and `false` is returned. `true` is returned when the next smaller permutation is successfully generated. |
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| The ordering relationship is determined by using `operator<` in the non-predicate versions, and by evaluating `pred` in the predicate versions. |
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| [heading Definition] |
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| Defined in the header file `boost/range/algorithm/permutation.hpp` |
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| [heading Requirements] |
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| [*For the non-predicate versions:] |
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| * `BidirectionalRange` is a model of the __bidirectional_range__ Concept. |
| * `BidirectionalRange` is mutable. |
| * `BidirectionalRange`'s value type is a model of the `LessThanComparableConcept`. |
| * The ordering of objects of type `BidirectionalRange`'s value type is a [*/strict weak ordering/], as defined in the `LessThanComparableConcept` requirements. |
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| [*For the predicate versions:] |
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| * `BidirectionalRange` is a model of the __bidirectional_range__ Concept. |
| * `BidirectionalRange` is mutable. |
| * `Compare` is a model of the `StrictWeakOrderingConcept`. |
| * `BidirectionalRange`'s value type is convertible to both of `Compare`'s argument types. |
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| [heading Complexity] |
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| Linear. At most `distance(rng) / 2` swaps. |
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| [endsect] |
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