template<class ForwardIterator1, class ForwardIterator2>
bool is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
ForwardIterator2 first2);
template<class ForwardIterator1, class ForwardIterator2,
class BinaryPredicate>
bool is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
ForwardIterator2 first2, BinaryPredicate pred);
template<class ForwardIterator1, class ForwardIterator2>
bool is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
ForwardIterator2 first2, ForwardIterator2 last2);
template<class ForwardIterator1, class ForwardIterator2,
class BinaryPredicate>
bool is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
ForwardIterator2 first2, ForwardIterator2 last2,
BinaryPredicate pred);
Requires: ForwardIterator1 and ForwardIterator2 shall have the same value type. The comparison function shall be an equivalence relation.
Remarks: If last2 was not given in the argument list, it denotes first2 + (last1 - first1) below.
Returns: If last1 - first1 != last2 - first2, return false. Otherwise return true if there exists a permutation of the elements in the range [first2,first2 + (last1 - first1)), beginning with ForwardIterator2 begin, such that equal(first1, last1, begin) returns true or 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 and last1 - first1 != last2 - first2. Otherwise, exactly distance(first1, last1) applications of the corresponding predicate if equal(first1, last1, first2, last2) would return true if pred was not given in the argument list or equal(first1, last1, first2, last2, pred) would return true if pred was given in the argument list; otherwise, at worst Ο(N2), where N has the value distance(first1, last1).