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Sprout/sprout/algorithm/is_permutation.hpp
2013-02-07 23:12:57 +09:00

129 lines
5.2 KiB
C++

#ifndef SPROUT_ALGORITHM_IS_PERMUTATION_HPP
#define SPROUT_ALGORITHM_IS_PERMUTATION_HPP
#include <iterator>
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/iterator/operation.hpp>
#include <sprout/iterator/type_traits/common.hpp>
#include <sprout/utility/pair/pair.hpp>
#include <sprout/functional/equal_to.hpp>
#include <sprout/functional/bind2nd.hpp>
#include <sprout/algorithm/count_if.hpp>
#include <sprout/detail/algorithm/count_n_if.hpp>
namespace sprout {
namespace detail {
template<typename RandomAccessIterator1, typename RandomAccessIterator2, typename BinaryPredicate>
inline SPROUT_CONSTEXPR bool
is_permutation_impl_ra(
RandomAccessIterator1 first1, RandomAccessIterator1 last1,
RandomAccessIterator2 first2, typename std::iterator_traits<RandomAccessIterator2>::difference_type d2,
BinaryPredicate pred,
typename std::iterator_traits<RandomAccessIterator1>::difference_type pivot
)
{
return pivot == 0 ? sprout::count_if(first1, last1, sprout::bind2nd(pred, *first1))
<= sprout::detail::count_n_if(first2, d2, sprout::bind2nd(pred, *first1))
: sprout::detail::is_permutation_impl_ra(
first1, last1, first2, d2,
pred, pivot / 2
)
&& sprout::detail::is_permutation_impl_ra(
sprout::next(first1, pivot), last1, first2, d2,
pred, (sprout::distance(first1, last1) - pivot) / 2
)
;
}
template<typename RandomAccessIterator1, typename RandomAccessIterator2, typename BinaryPredicate>
inline SPROUT_CONSTEXPR typename std::enable_if<
sprout::is_constant_distance_iterator<RandomAccessIterator1>::value && sprout::is_constant_distance_iterator<RandomAccessIterator2>::value,
bool
>::type
is_permutation(
RandomAccessIterator1 first1, RandomAccessIterator1 last1, RandomAccessIterator2 first2, BinaryPredicate pred,
std::random_access_iterator_tag*
)
{
return first1 == last1 ? true
: sprout::detail::is_permutation_impl_ra(
first1, last1, first2, sprout::distance(first1, last1),
pred, sprout::distance(first1, last1) / 2
)
;
}
template<typename ForwardIterator1, typename ForwardIterator2, typename BinaryPredicate>
inline SPROUT_CONSTEXPR sprout::pair<ForwardIterator1, bool>
is_permutation_impl_1(
sprout::pair<ForwardIterator1, bool> const& current,
ForwardIterator1 last1, ForwardIterator2 first2, typename std::iterator_traits<ForwardIterator2>::difference_type d2,
BinaryPredicate pred, typename std::iterator_traits<ForwardIterator1>::difference_type n
)
{
typedef sprout::pair<ForwardIterator1, bool> type;
return !current.second || current.first == last1 ? current
: n == 1 ? sprout::count_if(current.first, last1, sprout::bind2nd(pred, *current.first))
<= sprout::detail::count_n_if(first2, d2, sprout::bind2nd(pred, *current.first))
? type(sprout::next(current.first), true)
: type(current.first, false)
: sprout::detail::is_permutation_impl_1(
sprout::detail::is_permutation_impl_1(
current,
last1, first2, d2, pred, n / 2
),
last1, first2, d2, pred, n - n / 2
)
;
}
template<typename ForwardIterator1, typename ForwardIterator2, typename BinaryPredicate>
inline SPROUT_CONSTEXPR sprout::pair<ForwardIterator1, bool>
is_permutation_impl(
sprout::pair<ForwardIterator1, bool> const& current,
ForwardIterator1 last1, ForwardIterator2 first2, typename std::iterator_traits<ForwardIterator2>::difference_type d2,
BinaryPredicate pred, typename std::iterator_traits<ForwardIterator1>::difference_type n
)
{
typedef sprout::pair<ForwardIterator1, bool> type;
return !current.second || current.first == last1 ? current
: sprout::detail::is_permutation_impl(
sprout::detail::is_permutation_impl_1(
current,
last1, first2, d2, pred, n
),
last1, first2, d2, pred, n * 2
)
;
}
template<typename ForwardIterator1, typename ForwardIterator2, typename BinaryPredicate>
inline SPROUT_CONSTEXPR bool
is_permutation(
ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, BinaryPredicate pred,
void*
)
{
typedef sprout::pair<ForwardIterator1, bool> type;
return sprout::detail::is_permutation_impl(type(first1, true), last1, first2, sprout::distance(first1, last1), pred, 1).second;
}
} // namespace detail
// 25.2.12 Is permutation
//
// recursion depth:
// O(log N)
//
template<typename ForwardIterator1, typename ForwardIterator2, typename BinaryPredicate>
inline SPROUT_CONSTEXPR bool
is_permutation(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, BinaryPredicate pred) {
typedef typename sprout::common_iterator_category<ForwardIterator1, ForwardIterator2>::type* category;
return sprout::detail::is_permutation(first1, last1, first2, pred, category());
}
template<typename ForwardIterator1, typename ForwardIterator2>
inline SPROUT_CONSTEXPR bool
is_permutation(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2) {
return sprout::is_permutation(first1, last1, first2, sprout::equal_to<>());
}
} // namespace sprout
#endif // #ifndef SPROUT_ALGORITHM_IS_PERMUTATION_HPP