RhodeCode

/* -*- mode: C++; indent-tabs-mode: nil; -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library.

 *

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Research Group on Combinatorial Optimization, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

#ifndef RADIX_SORT_H

#define RADIX_SORT_H

/// \ingroup auxalg

/// \file

/// \brief Radix sort

///

/// Linear time sorting algorithms

#include <vector>

#include <limits>

#include <iterator>

#include <algorithm>

namespace lemon {

  namespace _radix_sort_bits {

    template <typename Value>

    struct Identity {

      const Value& operator()(const Value& val) {

        return val;

      }

    };

    template <typename Value, typename Iterator, typename Functor>

    Iterator radixSortPartition(Iterator first, Iterator last,

                                Functor functor, Value mask) {

      while (first != last && !(functor(*first) & mask)) {

        ++first;

      }

      if (first == last) {

        return first;

      }

      --last;

      while (first != last && (functor(*last) & mask)) {

        --last;

      }

      if (first == last) {

        return first;

      }

      std::iter_swap(first, last);

      ++first;

      if (!(first < last)) {

        return first;

      }

      while (true) {

        while (!(functor(*first) & mask)) {

          ++first;

        }

        target[counter[valueByte(functor(*it), byte)]++] = *it;

        ++it;

      }

    }

    template <typename Functor, typename Key>

    void signedStableRadixIntroSort(Key *first, Key *last, Key *target,

                                    int byte, Functor functor) {

      const int size =

        unsigned(std::numeric_limits<unsigned char>::max()) + 1;

      std::vector<int> counter(size);

      for (int i = 0; i < size; ++i) {

        counter[i] = 0;

      }

      Key *it = first;

      while (first != last) {

        counter[valueByte(functor(*first), byte)]++;

        ++first;

      }

      int prev, num = 0;

      for (int i = size / 2; i < size; ++i) {

        prev = num;

        num += counter[i];

        counter[i] = prev;

      }

      for (int i = 0; i < size / 2; ++i) {

        prev = num;

        num += counter[i];

        counter[i] = prev;

      }

      while (it != last) {

        target[counter[valueByte(functor(*it), byte)]++] = *it;

        ++it;

      }

    }

    template <typename Value, typename Iterator, typename Functor>

    void stableRadixSignedSort(Iterator first, Iterator last, Functor functor) {

      if (first == last) return;

      typedef typename std::iterator_traits<Iterator>::value_type Key;

      typedef std::allocator<Key> Allocator;

      Allocator allocator;

      int length = std::distance(first, last);

      Key* buffer = allocator.allocate(2 * length);

      try {

        bool dir = true;

        std::copy(first, last, buffer);

        for (int i = 0; i < int(sizeof(Value)) - 1; ++i) {

          if (dir) {

            stableRadixIntroSort(buffer, buffer + length, buffer + length,

                                 i, functor);

          } else {

            stableRadixIntroSort(buffer + length, buffer + 2 * length, buffer,

                                 i, functor);

          }

          dir = !dir;

        }

        if (dir) {

          signedStableRadixIntroSort(buffer, buffer + length, buffer + length,

                                     sizeof(Value) - 1, functor);

          std::copy(buffer + length, buffer + 2 * length, first);

        }        else {

                                     buffer, sizeof(Value) - 1, functor);

          std::copy(buffer, buffer + length, first);

        }

      } catch (...) {

        allocator.deallocate(buffer, 2 * length);

        throw;

      }

      allocator.deallocate(buffer, 2 * length);

    }

    template <typename Value, typename Iterator, typename Functor>

                                 Functor functor) {

      if (first == last) return;

      typedef typename std::iterator_traits<Iterator>::value_type Key;

      typedef std::allocator<Key> Allocator;

      Allocator allocator;

      int length = std::distance(first, last);

      Key *buffer = allocator.allocate(2 * length);

      try {

        bool dir = true;

        std::copy(first, last, buffer);

        for (int i = 0; i < int(sizeof(Value)); ++i) {

          if (dir) {

            stableRadixIntroSort(buffer, buffer + length,

                                 buffer + length, i, functor);

          } else {

            stableRadixIntroSort(buffer + length, buffer + 2 * length,

                                 buffer, i, functor);

          }

          dir = !dir;

        }

        if (dir) {

          std::copy(buffer, buffer + length, first);

        }        else {

          std::copy(buffer + length, buffer + 2 * length, first);

        }

      } catch (...) {

        allocator.deallocate(buffer, 2 * length);

        throw;

      }

      allocator.deallocate(buffer, 2 * length);

    }

    template <typename Value,

              bool sign = std::numeric_limits<Value>::is_signed >

    struct StableRadixSortSelector {

      template <typename Iterator, typename Functor>

      static void sort(Iterator first, Iterator last, Functor functor) {

        stableRadixSignedSort<Value>(first, last, functor);

      }

    };

    template <typename Value>

    struct StableRadixSortSelector<Value, false> {

      template <typename Iterator, typename Functor>

      static void sort(Iterator first, Iterator last, Functor functor) {

        stableRadixUnsignedSort<Value>(first, last, functor);

      }

    };

  }

  /// \ingroup auxalg

  ///

  /// \brief Sorts the STL compatible range into ascending order in a stable

  /// way.

  ///

  /// This function sorts an STL compatible range into ascending

  /// order according to an integer mapping in the same as radixSort() does.

  ///

  /// This sorting algorithm is stable, i.e. the order of two equal

  /// elements remains the same after the sorting.

/* -*- mode: C++; indent-tabs-mode: nil; -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library.

 *

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Research Group on Combinatorial Optimization, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

#include <lemon/time_measure.h>

#include <lemon/smart_graph.h>

#include <lemon/maps.h>

#include <lemon/radix_sort.h>

#include <lemon/math.h>

#include "test_tools.h"

#include <vector>

#include <algorithm>

using namespace lemon;

static const int n = 10000;

struct Negate {

  typedef int argument_type;

  typedef int result_type;

  int operator()(int a) { return - a; }

};

int negate(int a) { return - a; }

void generateIntSequence(int n, std::vector<int>& data) {

  int prime = 9973;

  int root = 136, value = 1;

  for (int i = 0; i < n; ++i) {

    data.push_back(value - prime / 2);

    value = (value * root) % prime;

  }

}

void generateCharSequence(int n, std::vector<unsigned char>& data) {

  int prime = 251;

  int root = 3, value = root;

  for (int i = 0; i < n; ++i) {

    data.push_back(static_cast<unsigned char>(value));

    value = (value * root) % prime;

  }

}

void checkRadixSort() {

  {

    std::vector<int> data1;

    generateIntSequence(n, data1);

    std::vector<int> data2(data1);

    std::sort(data1.begin(), data1.end());

    radixSort(data2.begin(), data2.end());