6.4 KiB
[alg.is.permutation]
26 Algorithms library [algorithms]
26.6 Non-modifying sequence operations [alg.nonmodifying]
26.6.14 Is permutation [alg.is.permutation]
template<class ForwardIterator1, class ForwardIterator2> constexpr bool is_permutation(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2); template<class ForwardIterator1, class ForwardIterator2, class BinaryPredicate> constexpr bool is_permutation(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, BinaryPredicate pred); template<class ForwardIterator1, class ForwardIterator2> constexpr bool is_permutation(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, ForwardIterator2 last2); template<class ForwardIterator1, class ForwardIterator2, class BinaryPredicate> constexpr bool is_permutation(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, ForwardIterator2 last2, BinaryPredicate pred);
Let last2 be first2 + (last1 - first1) for the overloads with no parameter named last2, and let pred be equal_to{} for the overloads with no parameter pred.
Mandates: ForwardIterator1 and ForwardIterator2 have the same value type.
Preconditions: The comparison function is an equivalence relation.
Returns: If last1 - first1 != last2 - first2, return false.
Otherwise return true if there exists a permutation of the elements in the range [first2, last2), beginning with ForwardIterator2 begin, such that equal(first1, last1, begin, pred) returns true; otherwise, returns false.
Complexity: No applications of the corresponding predicate if ForwardIterator1 and ForwardIterator2 meet the requirements of random access iterators andlast1 - first1 != last2 - first2.
Otherwise, exactly last1 - first1 applications of the corresponding predicate if equal(first1, last1, first2, last2, pred) would return true; otherwise, at worst O(N2), where N has the value last1 - first1.
template<[forward_iterator](iterator.concept.forward#concept:forward_iterator "24.3.4.11 Concept forward_iterator [iterator.concept.forward]") I1, [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7 Concept sentinel_for [iterator.concept.sentinel]")<I1> S1, [forward_iterator](iterator.concept.forward#concept:forward_iterator "24.3.4.11 Concept forward_iterator [iterator.concept.forward]") I2, [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7 Concept sentinel_for [iterator.concept.sentinel]")<I2> S2, class Proj1 = identity, class Proj2 = identity, [indirect_equivalence_relation](indirectcallable.indirectinvocable#concept:indirect_equivalence_relation "24.3.6.3 Indirect callables [indirectcallable.indirectinvocable]")<projected<I1, Proj1>, projected<I2, Proj2>> Pred = ranges::equal_to> constexpr bool ranges::is_permutation(I1 first1, S1 last1, I2 first2, S2 last2, Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {}); template<[forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]") R1, [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]") R2, class Proj1 = identity, class Proj2 = identity, [indirect_equivalence_relation](indirectcallable.indirectinvocable#concept:indirect_equivalence_relation "24.3.6.3 Indirect callables [indirectcallable.indirectinvocable]")<projected<iterator_t<R1>, Proj1>, projected<iterator_t<R2>, Proj2>> Pred = ranges::equal_to> constexpr bool ranges::is_permutation(R1&& r1, R2&& r2, Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {});
Returns: If last1 - first1 != last2 - first2, return false.
Otherwise return true if there exists a permutation of the elements in the range [first2, last2), bounded by [pfirst, plast), such thatranges::equal(first1, last1, pfirst, plast, pred, proj1, proj2) returns true; otherwise, returns false.
Complexity: No applications of the corresponding predicate and projections if
for the first overload,
S1 and I1 model sized_sentinel_for<S1, I1>,
S2 and I2 model sized_sentinel_for<S2, I2>, and
last1 - first1 != last2 - first2;
for the second overload,R1 and R2 each model sized_range, andranges::distance(r1) != ranges::distance(r2).
Otherwise, exactly last1 - first1 applications of the corresponding predicate and projections if ranges::equal(first1, last1, first2, last2, pred, proj1, proj2) would return true; otherwise, at worst O(N2), where N has the value last1 - first1.