645 lines
22 KiB
C++
645 lines
22 KiB
C++
// -*- C++ -*-
|
|
|
|
// Copyright (C) 2007-2021 Free Software Foundation, Inc.
|
|
//
|
|
// This file is part of the GNU ISO C++ Library. This library is free
|
|
// software; you can redistribute it and/or modify it under the terms
|
|
// of the GNU General Public License as published by the Free Software
|
|
// Foundation; either version 3, or (at your option) any later
|
|
// version.
|
|
|
|
// This library is distributed in the hope that it will be useful, but
|
|
// WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
// General Public License for more details.
|
|
|
|
// Under Section 7 of GPL version 3, you are granted additional
|
|
// permissions described in the GCC Runtime Library Exception, version
|
|
// 3.1, as published by the Free Software Foundation.
|
|
|
|
// You should have received a copy of the GNU General Public License and
|
|
// a copy of the GCC Runtime Library Exception along with this program;
|
|
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
|
|
// <http://www.gnu.org/licenses/>.
|
|
|
|
/** @file parallel/multiseq_selection.h
|
|
* @brief Functions to find elements of a certain global __rank in
|
|
* multiple sorted sequences. Also serves for splitting such
|
|
* sequence sets.
|
|
*
|
|
* The algorithm description can be found in
|
|
*
|
|
* P. J. Varman, S. D. Scheufler, B. R. Iyer, and G. R. Ricard.
|
|
* Merging Multiple Lists on Hierarchical-Memory Multiprocessors.
|
|
* Journal of Parallel and Distributed Computing, 12(2):171-177, 1991.
|
|
*
|
|
* This file is a GNU parallel extension to the Standard C++ Library.
|
|
*/
|
|
|
|
// Written by Johannes Singler.
|
|
|
|
#ifndef _GLIBCXX_PARALLEL_MULTISEQ_SELECTION_H
|
|
#define _GLIBCXX_PARALLEL_MULTISEQ_SELECTION_H 1
|
|
|
|
#include <vector>
|
|
#include <queue>
|
|
|
|
#include <bits/stl_algo.h>
|
|
|
|
namespace __gnu_parallel
|
|
{
|
|
/** @brief Compare __a pair of types lexicographically, ascending. */
|
|
template<typename _T1, typename _T2, typename _Compare>
|
|
class _Lexicographic
|
|
: public std::binary_function<std::pair<_T1, _T2>,
|
|
std::pair<_T1, _T2>, bool>
|
|
{
|
|
private:
|
|
_Compare& _M_comp;
|
|
|
|
public:
|
|
_Lexicographic(_Compare& __comp) : _M_comp(__comp) { }
|
|
|
|
bool
|
|
operator()(const std::pair<_T1, _T2>& __p1,
|
|
const std::pair<_T1, _T2>& __p2) const
|
|
{
|
|
if (_M_comp(__p1.first, __p2.first))
|
|
return true;
|
|
|
|
if (_M_comp(__p2.first, __p1.first))
|
|
return false;
|
|
|
|
// Firsts are equal.
|
|
return __p1.second < __p2.second;
|
|
}
|
|
};
|
|
|
|
/** @brief Compare __a pair of types lexicographically, descending. */
|
|
template<typename _T1, typename _T2, typename _Compare>
|
|
class _LexicographicReverse : public std::binary_function<_T1, _T2, bool>
|
|
{
|
|
private:
|
|
_Compare& _M_comp;
|
|
|
|
public:
|
|
_LexicographicReverse(_Compare& __comp) : _M_comp(__comp) { }
|
|
|
|
bool
|
|
operator()(const std::pair<_T1, _T2>& __p1,
|
|
const std::pair<_T1, _T2>& __p2) const
|
|
{
|
|
if (_M_comp(__p2.first, __p1.first))
|
|
return true;
|
|
|
|
if (_M_comp(__p1.first, __p2.first))
|
|
return false;
|
|
|
|
// Firsts are equal.
|
|
return __p2.second < __p1.second;
|
|
}
|
|
};
|
|
|
|
/**
|
|
* @brief Splits several sorted sequences at a certain global __rank,
|
|
* resulting in a splitting point for each sequence.
|
|
* The sequences are passed via a sequence of random-access
|
|
* iterator pairs, none of the sequences may be empty. If there
|
|
* are several equal elements across the split, the ones on the
|
|
* __left side will be chosen from sequences with smaller number.
|
|
* @param __begin_seqs Begin of the sequence of iterator pairs.
|
|
* @param __end_seqs End of the sequence of iterator pairs.
|
|
* @param __rank The global rank to partition at.
|
|
* @param __begin_offsets A random-access __sequence __begin where the
|
|
* __result will be stored in. Each element of the sequence is an
|
|
* iterator that points to the first element on the greater part of
|
|
* the respective __sequence.
|
|
* @param __comp The ordering functor, defaults to std::less<_Tp>.
|
|
*/
|
|
template<typename _RanSeqs, typename _RankType, typename _RankIterator,
|
|
typename _Compare>
|
|
void
|
|
multiseq_partition(_RanSeqs __begin_seqs, _RanSeqs __end_seqs,
|
|
_RankType __rank,
|
|
_RankIterator __begin_offsets,
|
|
_Compare __comp = std::less<
|
|
typename std::iterator_traits<typename
|
|
std::iterator_traits<_RanSeqs>::value_type::
|
|
first_type>::value_type>()) // std::less<_Tp>
|
|
{
|
|
_GLIBCXX_CALL(__end_seqs - __begin_seqs)
|
|
|
|
typedef typename std::iterator_traits<_RanSeqs>::value_type::first_type
|
|
_It;
|
|
typedef typename std::iterator_traits<_RanSeqs>::difference_type
|
|
_SeqNumber;
|
|
typedef typename std::iterator_traits<_It>::difference_type
|
|
_DifferenceType;
|
|
typedef typename std::iterator_traits<_It>::value_type _ValueType;
|
|
|
|
_Lexicographic<_ValueType, _SeqNumber, _Compare> __lcomp(__comp);
|
|
_LexicographicReverse<_ValueType, _SeqNumber, _Compare> __lrcomp(__comp);
|
|
|
|
// Number of sequences, number of elements in total (possibly
|
|
// including padding).
|
|
_DifferenceType __m = std::distance(__begin_seqs, __end_seqs), __nn = 0,
|
|
__nmax, __n, __r;
|
|
|
|
for (_SeqNumber __i = 0; __i < __m; __i++)
|
|
{
|
|
__nn += std::distance(__begin_seqs[__i].first,
|
|
__begin_seqs[__i].second);
|
|
_GLIBCXX_PARALLEL_ASSERT(
|
|
std::distance(__begin_seqs[__i].first,
|
|
__begin_seqs[__i].second) > 0);
|
|
}
|
|
|
|
if (__rank == __nn)
|
|
{
|
|
for (_SeqNumber __i = 0; __i < __m; __i++)
|
|
__begin_offsets[__i] = __begin_seqs[__i].second; // Very end.
|
|
// Return __m - 1;
|
|
return;
|
|
}
|
|
|
|
_GLIBCXX_PARALLEL_ASSERT(__m != 0);
|
|
_GLIBCXX_PARALLEL_ASSERT(__nn != 0);
|
|
_GLIBCXX_PARALLEL_ASSERT(__rank >= 0);
|
|
_GLIBCXX_PARALLEL_ASSERT(__rank < __nn);
|
|
|
|
_DifferenceType* __ns = new _DifferenceType[__m];
|
|
_DifferenceType* __a = new _DifferenceType[__m];
|
|
_DifferenceType* __b = new _DifferenceType[__m];
|
|
_DifferenceType __l;
|
|
|
|
__ns[0] = std::distance(__begin_seqs[0].first, __begin_seqs[0].second);
|
|
__nmax = __ns[0];
|
|
for (_SeqNumber __i = 0; __i < __m; __i++)
|
|
{
|
|
__ns[__i] = std::distance(__begin_seqs[__i].first,
|
|
__begin_seqs[__i].second);
|
|
__nmax = std::max(__nmax, __ns[__i]);
|
|
}
|
|
|
|
__r = __rd_log2(__nmax) + 1;
|
|
|
|
// Pad all lists to this length, at least as long as any ns[__i],
|
|
// equality iff __nmax = 2^__k - 1.
|
|
__l = (1ULL << __r) - 1;
|
|
|
|
for (_SeqNumber __i = 0; __i < __m; __i++)
|
|
{
|
|
__a[__i] = 0;
|
|
__b[__i] = __l;
|
|
}
|
|
__n = __l / 2;
|
|
|
|
// Invariants:
|
|
// 0 <= __a[__i] <= __ns[__i], 0 <= __b[__i] <= __l
|
|
|
|
#define __S(__i) (__begin_seqs[__i].first)
|
|
|
|
// Initial partition.
|
|
std::vector<std::pair<_ValueType, _SeqNumber> > __sample;
|
|
|
|
for (_SeqNumber __i = 0; __i < __m; __i++)
|
|
if (__n < __ns[__i]) //__sequence long enough
|
|
__sample.push_back(std::make_pair(__S(__i)[__n], __i));
|
|
__gnu_sequential::sort(__sample.begin(), __sample.end(), __lcomp);
|
|
|
|
for (_SeqNumber __i = 0; __i < __m; __i++) //conceptual infinity
|
|
if (__n >= __ns[__i]) //__sequence too short, conceptual infinity
|
|
__sample.push_back(
|
|
std::make_pair(__S(__i)[0] /*__dummy element*/, __i));
|
|
|
|
_DifferenceType __localrank = __rank / __l;
|
|
|
|
_SeqNumber __j;
|
|
for (__j = 0;
|
|
__j < __localrank && ((__n + 1) <= __ns[__sample[__j].second]);
|
|
++__j)
|
|
__a[__sample[__j].second] += __n + 1;
|
|
for (; __j < __m; __j++)
|
|
__b[__sample[__j].second] -= __n + 1;
|
|
|
|
// Further refinement.
|
|
while (__n > 0)
|
|
{
|
|
__n /= 2;
|
|
|
|
_SeqNumber __lmax_seq = -1; // to avoid warning
|
|
const _ValueType* __lmax = 0; // impossible to avoid the warning?
|
|
for (_SeqNumber __i = 0; __i < __m; __i++)
|
|
{
|
|
if (__a[__i] > 0)
|
|
{
|
|
if (!__lmax)
|
|
{
|
|
__lmax = &(__S(__i)[__a[__i] - 1]);
|
|
__lmax_seq = __i;
|
|
}
|
|
else
|
|
{
|
|
// Max, favor rear sequences.
|
|
if (!__comp(__S(__i)[__a[__i] - 1], *__lmax))
|
|
{
|
|
__lmax = &(__S(__i)[__a[__i] - 1]);
|
|
__lmax_seq = __i;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
_SeqNumber __i;
|
|
for (__i = 0; __i < __m; __i++)
|
|
{
|
|
_DifferenceType __middle = (__b[__i] + __a[__i]) / 2;
|
|
if (__lmax && __middle < __ns[__i] &&
|
|
__lcomp(std::make_pair(__S(__i)[__middle], __i),
|
|
std::make_pair(*__lmax, __lmax_seq)))
|
|
__a[__i] = std::min(__a[__i] + __n + 1, __ns[__i]);
|
|
else
|
|
__b[__i] -= __n + 1;
|
|
}
|
|
|
|
_DifferenceType __leftsize = 0;
|
|
for (_SeqNumber __i = 0; __i < __m; __i++)
|
|
__leftsize += __a[__i] / (__n + 1);
|
|
|
|
_DifferenceType __skew = __rank / (__n + 1) - __leftsize;
|
|
|
|
if (__skew > 0)
|
|
{
|
|
// Move to the left, find smallest.
|
|
std::priority_queue<std::pair<_ValueType, _SeqNumber>,
|
|
std::vector<std::pair<_ValueType, _SeqNumber> >,
|
|
_LexicographicReverse<_ValueType, _SeqNumber, _Compare> >
|
|
__pq(__lrcomp);
|
|
|
|
for (_SeqNumber __i = 0; __i < __m; __i++)
|
|
if (__b[__i] < __ns[__i])
|
|
__pq.push(std::make_pair(__S(__i)[__b[__i]], __i));
|
|
|
|
for (; __skew != 0 && !__pq.empty(); --__skew)
|
|
{
|
|
_SeqNumber __source = __pq.top().second;
|
|
__pq.pop();
|
|
|
|
__a[__source]
|
|
= std::min(__a[__source] + __n + 1, __ns[__source]);
|
|
__b[__source] += __n + 1;
|
|
|
|
if (__b[__source] < __ns[__source])
|
|
__pq.push(
|
|
std::make_pair(__S(__source)[__b[__source]], __source));
|
|
}
|
|
}
|
|
else if (__skew < 0)
|
|
{
|
|
// Move to the right, find greatest.
|
|
std::priority_queue<std::pair<_ValueType, _SeqNumber>,
|
|
std::vector<std::pair<_ValueType, _SeqNumber> >,
|
|
_Lexicographic<_ValueType, _SeqNumber, _Compare> >
|
|
__pq(__lcomp);
|
|
|
|
for (_SeqNumber __i = 0; __i < __m; __i++)
|
|
if (__a[__i] > 0)
|
|
__pq.push(std::make_pair(__S(__i)[__a[__i] - 1], __i));
|
|
|
|
for (; __skew != 0; ++__skew)
|
|
{
|
|
_SeqNumber __source = __pq.top().second;
|
|
__pq.pop();
|
|
|
|
__a[__source] -= __n + 1;
|
|
__b[__source] -= __n + 1;
|
|
|
|
if (__a[__source] > 0)
|
|
__pq.push(std::make_pair(
|
|
__S(__source)[__a[__source] - 1], __source));
|
|
}
|
|
}
|
|
}
|
|
|
|
// Postconditions:
|
|
// __a[__i] == __b[__i] in most cases, except when __a[__i] has been
|
|
// clamped because of having reached the boundary
|
|
|
|
// Now return the result, calculate the offset.
|
|
|
|
// Compare the keys on both edges of the border.
|
|
|
|
// Maximum of left edge, minimum of right edge.
|
|
_ValueType* __maxleft = 0;
|
|
_ValueType* __minright = 0;
|
|
for (_SeqNumber __i = 0; __i < __m; __i++)
|
|
{
|
|
if (__a[__i] > 0)
|
|
{
|
|
if (!__maxleft)
|
|
__maxleft = &(__S(__i)[__a[__i] - 1]);
|
|
else
|
|
{
|
|
// Max, favor rear sequences.
|
|
if (!__comp(__S(__i)[__a[__i] - 1], *__maxleft))
|
|
__maxleft = &(__S(__i)[__a[__i] - 1]);
|
|
}
|
|
}
|
|
if (__b[__i] < __ns[__i])
|
|
{
|
|
if (!__minright)
|
|
__minright = &(__S(__i)[__b[__i]]);
|
|
else
|
|
{
|
|
// Min, favor fore sequences.
|
|
if (__comp(__S(__i)[__b[__i]], *__minright))
|
|
__minright = &(__S(__i)[__b[__i]]);
|
|
}
|
|
}
|
|
}
|
|
|
|
_SeqNumber __seq = 0;
|
|
for (_SeqNumber __i = 0; __i < __m; __i++)
|
|
__begin_offsets[__i] = __S(__i) + __a[__i];
|
|
|
|
delete[] __ns;
|
|
delete[] __a;
|
|
delete[] __b;
|
|
}
|
|
|
|
|
|
/**
|
|
* @brief Selects the element at a certain global __rank from several
|
|
* sorted sequences.
|
|
*
|
|
* The sequences are passed via a sequence of random-access
|
|
* iterator pairs, none of the sequences may be empty.
|
|
* @param __begin_seqs Begin of the sequence of iterator pairs.
|
|
* @param __end_seqs End of the sequence of iterator pairs.
|
|
* @param __rank The global rank to partition at.
|
|
* @param __offset The rank of the selected element in the global
|
|
* subsequence of elements equal to the selected element. If the
|
|
* selected element is unique, this number is 0.
|
|
* @param __comp The ordering functor, defaults to std::less.
|
|
*/
|
|
template<typename _Tp, typename _RanSeqs, typename _RankType,
|
|
typename _Compare>
|
|
_Tp
|
|
multiseq_selection(_RanSeqs __begin_seqs, _RanSeqs __end_seqs,
|
|
_RankType __rank,
|
|
_RankType& __offset, _Compare __comp = std::less<_Tp>())
|
|
{
|
|
_GLIBCXX_CALL(__end_seqs - __begin_seqs)
|
|
|
|
typedef typename std::iterator_traits<_RanSeqs>::value_type::first_type
|
|
_It;
|
|
typedef typename std::iterator_traits<_RanSeqs>::difference_type
|
|
_SeqNumber;
|
|
typedef typename std::iterator_traits<_It>::difference_type
|
|
_DifferenceType;
|
|
|
|
_Lexicographic<_Tp, _SeqNumber, _Compare> __lcomp(__comp);
|
|
_LexicographicReverse<_Tp, _SeqNumber, _Compare> __lrcomp(__comp);
|
|
|
|
// Number of sequences, number of elements in total (possibly
|
|
// including padding).
|
|
_DifferenceType __m = std::distance(__begin_seqs, __end_seqs);
|
|
_DifferenceType __nn = 0;
|
|
_DifferenceType __nmax, __n, __r;
|
|
|
|
for (_SeqNumber __i = 0; __i < __m; __i++)
|
|
__nn += std::distance(__begin_seqs[__i].first,
|
|
__begin_seqs[__i].second);
|
|
|
|
if (__m == 0 || __nn == 0 || __rank < 0 || __rank >= __nn)
|
|
{
|
|
// result undefined if there is no data or __rank is outside bounds
|
|
throw std::exception();
|
|
}
|
|
|
|
|
|
_DifferenceType* __ns = new _DifferenceType[__m];
|
|
_DifferenceType* __a = new _DifferenceType[__m];
|
|
_DifferenceType* __b = new _DifferenceType[__m];
|
|
_DifferenceType __l;
|
|
|
|
__ns[0] = std::distance(__begin_seqs[0].first, __begin_seqs[0].second);
|
|
__nmax = __ns[0];
|
|
for (_SeqNumber __i = 0; __i < __m; ++__i)
|
|
{
|
|
__ns[__i] = std::distance(__begin_seqs[__i].first,
|
|
__begin_seqs[__i].second);
|
|
__nmax = std::max(__nmax, __ns[__i]);
|
|
}
|
|
|
|
__r = __rd_log2(__nmax) + 1;
|
|
|
|
// Pad all lists to this length, at least as long as any ns[__i],
|
|
// equality iff __nmax = 2^__k - 1
|
|
__l = __round_up_to_pow2(__r) - 1;
|
|
|
|
for (_SeqNumber __i = 0; __i < __m; ++__i)
|
|
{
|
|
__a[__i] = 0;
|
|
__b[__i] = __l;
|
|
}
|
|
__n = __l / 2;
|
|
|
|
// Invariants:
|
|
// 0 <= __a[__i] <= __ns[__i], 0 <= __b[__i] <= __l
|
|
|
|
#define __S(__i) (__begin_seqs[__i].first)
|
|
|
|
// Initial partition.
|
|
std::vector<std::pair<_Tp, _SeqNumber> > __sample;
|
|
|
|
for (_SeqNumber __i = 0; __i < __m; __i++)
|
|
if (__n < __ns[__i])
|
|
__sample.push_back(std::make_pair(__S(__i)[__n], __i));
|
|
__gnu_sequential::sort(__sample.begin(), __sample.end(),
|
|
__lcomp, sequential_tag());
|
|
|
|
// Conceptual infinity.
|
|
for (_SeqNumber __i = 0; __i < __m; __i++)
|
|
if (__n >= __ns[__i])
|
|
__sample.push_back(
|
|
std::make_pair(__S(__i)[0] /*__dummy element*/, __i));
|
|
|
|
_DifferenceType __localrank = __rank / __l;
|
|
|
|
_SeqNumber __j;
|
|
for (__j = 0;
|
|
__j < __localrank && ((__n + 1) <= __ns[__sample[__j].second]);
|
|
++__j)
|
|
__a[__sample[__j].second] += __n + 1;
|
|
for (; __j < __m; ++__j)
|
|
__b[__sample[__j].second] -= __n + 1;
|
|
|
|
// Further refinement.
|
|
while (__n > 0)
|
|
{
|
|
__n /= 2;
|
|
|
|
const _Tp* __lmax = 0;
|
|
for (_SeqNumber __i = 0; __i < __m; ++__i)
|
|
{
|
|
if (__a[__i] > 0)
|
|
{
|
|
if (!__lmax)
|
|
__lmax = &(__S(__i)[__a[__i] - 1]);
|
|
else
|
|
{
|
|
if (__comp(*__lmax, __S(__i)[__a[__i] - 1])) //max
|
|
__lmax = &(__S(__i)[__a[__i] - 1]);
|
|
}
|
|
}
|
|
}
|
|
|
|
_SeqNumber __i;
|
|
for (__i = 0; __i < __m; __i++)
|
|
{
|
|
_DifferenceType __middle = (__b[__i] + __a[__i]) / 2;
|
|
if (__lmax && __middle < __ns[__i]
|
|
&& __comp(__S(__i)[__middle], *__lmax))
|
|
__a[__i] = std::min(__a[__i] + __n + 1, __ns[__i]);
|
|
else
|
|
__b[__i] -= __n + 1;
|
|
}
|
|
|
|
_DifferenceType __leftsize = 0;
|
|
for (_SeqNumber __i = 0; __i < __m; ++__i)
|
|
__leftsize += __a[__i] / (__n + 1);
|
|
|
|
_DifferenceType __skew = __rank / (__n + 1) - __leftsize;
|
|
|
|
if (__skew > 0)
|
|
{
|
|
// Move to the left, find smallest.
|
|
std::priority_queue<std::pair<_Tp, _SeqNumber>,
|
|
std::vector<std::pair<_Tp, _SeqNumber> >,
|
|
_LexicographicReverse<_Tp, _SeqNumber, _Compare> >
|
|
__pq(__lrcomp);
|
|
|
|
for (_SeqNumber __i = 0; __i < __m; ++__i)
|
|
if (__b[__i] < __ns[__i])
|
|
__pq.push(std::make_pair(__S(__i)[__b[__i]], __i));
|
|
|
|
for (; __skew != 0 && !__pq.empty(); --__skew)
|
|
{
|
|
_SeqNumber __source = __pq.top().second;
|
|
__pq.pop();
|
|
|
|
__a[__source]
|
|
= std::min(__a[__source] + __n + 1, __ns[__source]);
|
|
__b[__source] += __n + 1;
|
|
|
|
if (__b[__source] < __ns[__source])
|
|
__pq.push(
|
|
std::make_pair(__S(__source)[__b[__source]], __source));
|
|
}
|
|
}
|
|
else if (__skew < 0)
|
|
{
|
|
// Move to the right, find greatest.
|
|
std::priority_queue<std::pair<_Tp, _SeqNumber>,
|
|
std::vector<std::pair<_Tp, _SeqNumber> >,
|
|
_Lexicographic<_Tp, _SeqNumber, _Compare> > __pq(__lcomp);
|
|
|
|
for (_SeqNumber __i = 0; __i < __m; ++__i)
|
|
if (__a[__i] > 0)
|
|
__pq.push(std::make_pair(__S(__i)[__a[__i] - 1], __i));
|
|
|
|
for (; __skew != 0; ++__skew)
|
|
{
|
|
_SeqNumber __source = __pq.top().second;
|
|
__pq.pop();
|
|
|
|
__a[__source] -= __n + 1;
|
|
__b[__source] -= __n + 1;
|
|
|
|
if (__a[__source] > 0)
|
|
__pq.push(std::make_pair(
|
|
__S(__source)[__a[__source] - 1], __source));
|
|
}
|
|
}
|
|
}
|
|
|
|
// Postconditions:
|
|
// __a[__i] == __b[__i] in most cases, except when __a[__i] has been
|
|
// clamped because of having reached the boundary
|
|
|
|
// Now return the result, calculate the offset.
|
|
|
|
// Compare the keys on both edges of the border.
|
|
|
|
// Maximum of left edge, minimum of right edge.
|
|
bool __maxleftset = false, __minrightset = false;
|
|
|
|
// Impossible to avoid the warning?
|
|
_Tp __maxleft, __minright;
|
|
for (_SeqNumber __i = 0; __i < __m; ++__i)
|
|
{
|
|
if (__a[__i] > 0)
|
|
{
|
|
if (!__maxleftset)
|
|
{
|
|
__maxleft = __S(__i)[__a[__i] - 1];
|
|
__maxleftset = true;
|
|
}
|
|
else
|
|
{
|
|
// Max.
|
|
if (__comp(__maxleft, __S(__i)[__a[__i] - 1]))
|
|
__maxleft = __S(__i)[__a[__i] - 1];
|
|
}
|
|
}
|
|
if (__b[__i] < __ns[__i])
|
|
{
|
|
if (!__minrightset)
|
|
{
|
|
__minright = __S(__i)[__b[__i]];
|
|
__minrightset = true;
|
|
}
|
|
else
|
|
{
|
|
// Min.
|
|
if (__comp(__S(__i)[__b[__i]], __minright))
|
|
__minright = __S(__i)[__b[__i]];
|
|
}
|
|
}
|
|
}
|
|
|
|
// Minright is the __splitter, in any case.
|
|
|
|
if (!__maxleftset || __comp(__minright, __maxleft))
|
|
{
|
|
// Good luck, everything is split unambiguously.
|
|
__offset = 0;
|
|
}
|
|
else
|
|
{
|
|
// We have to calculate an offset.
|
|
__offset = 0;
|
|
|
|
for (_SeqNumber __i = 0; __i < __m; ++__i)
|
|
{
|
|
_DifferenceType lb
|
|
= std::lower_bound(__S(__i), __S(__i) + __ns[__i],
|
|
__minright,
|
|
__comp) - __S(__i);
|
|
__offset += __a[__i] - lb;
|
|
}
|
|
}
|
|
|
|
delete[] __ns;
|
|
delete[] __a;
|
|
delete[] __b;
|
|
|
|
return __minright;
|
|
}
|
|
}
|
|
|
|
#undef __S
|
|
|
|
#endif /* _GLIBCXX_PARALLEL_MULTISEQ_SELECTION_H */
|