Algo/sort_algo.hpp at master · ExMix/Algo · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
//
// Created by Yury Rakhuba on 24/07/15.
//

#pragma once

#include "iter_traits.hpp"

#include <iterator>
#include <vector>

namespace sort
{

template <typename TIter, typename TLess>
void SelectionSort(TIter const & beg, TIter const & end, TLess const & cmp)
{
  static_assert(iter::ForwardIterCheck<TIter>::value, "");

  for (TIter outerIter = beg; outerIter != end; ++outerIter)
  {
    TIter minElement = outerIter;
    for (TIter innerIter = iter::NextIter(outerIter, 1); innerIter != end; ++innerIter)
    {
      if (cmp(*innerIter, *minElement))
        minElement = innerIter;
    }

    iter::SwapValues(outerIter, minElement);
  }
}

template <typename TIter>
void SelectionSort(TIter const & beg, TIter const & end)
{
  SelectionSort(beg, end, std::less<typename std::iterator_traits<TIter>::value_type>());
}

template <typename TIter, typename TLess>
void InsertionSort(TIter const & beg, TIter const & end, TLess const & cmp)
{
  static_assert(iter::BidirIterCheck<TIter>::value, "");

  for (TIter outerIter = iter::NextIter(beg, 1); outerIter != end; ++outerIter)
  {
    TIter innerIter = outerIter;
    TIter prevIter = iter::NextIter(innerIter, -1);
    while (innerIter != beg && cmp(*innerIter, *prevIter))
    {
      iter::SwapValues(innerIter, prevIter);
      innerIter = prevIter;
      prevIter = iter::NextIter(innerIter, -1);
    }
  }
}

template <typename TIter>
void InsertionSort(TIter const & beg, TIter const & end)
{
  InsertionSort(beg, end, std::less<typename std::iterator_traits<TIter>::value_type>());
};

template <typename TIter, typename TLess>
void BubbleSort(TIter const & beg, TIter const & end, TLess const & cmp)
{
  static_assert(iter::ForwardIterCheck<TIter>::value, "");

  for (TIter i = beg; i != end; ++i)
  {
    for (TIter j = iter::NextIter(i, 1); j != end; ++j)
    {
      if (cmp(*j, *i))
        iter::SwapValues(i, j);
    }
  }
};

template <typename TIter>
void BubbleSort(TIter const & beg, TIter const & end)
{
  BubbleSort(beg, end, std::less<typename std::iterator_traits<TIter>::value_type>());
}

namespace impl
{

template <typename TIter>
void FindMergeRange(TIter & beg1, TIter end1, TIter & beg2, TIter end2)
{
  static_assert(iter::ForwardIterCheck<TIter>::value, "");

  if (beg1 == end1)
  {
    assert(beg2 != end2);
    beg2 = end2;
    return;
  }

  if (beg2 == end2)
  {
    beg1 = end1;
    return;
  }

  if (*beg2 < *beg1)
  {
    FindMergeRange(beg2, end2, beg1, end1);
  }
  else
  {
    while (beg1 != end1 && *beg1 <= *beg2)
      ++beg1;
  }
}

template <typename TInsertIter, typename TIter>
void Merge(TInsertIter output, TIter const & beg1, TIter const & end1, TIter const & beg2, TIter const & end2)
{
  static_assert(iter::ForwardIterCheck<TIter>::value, "");
  //static_assert(iter::OutputIterCheck<TInsertIter>::value, "");

  TIter start1 = beg1;
  TIter mid1 = start1;
  TIter start2 = beg2;
  TIter mid2 = start2;

  auto copyFn = [](TInsertIter & output, TIter & b, TIter & e)
  {
    std::copy(b, e, output);
    std::advance(output, std::distance(b, e));
    b = e;
  };

  while (mid1 != end1 || mid2 != end2)
  {
    FindMergeRange(mid1, end1, mid2, end2);
    copyFn(output, start1, mid1);
    copyFn(output, start2, mid2);
  }
};

} // namespace impl

template <typename TIter>
void MergeSort(TIter beg, TIter end)
{
  static_assert(iter::ForwardIterCheck<TIter>::value, "");
  //static_assert(iter::OutputIterCheck<TIter>::value, "");

  size_t dist = std::distance(beg, end);
  using TValue = typename std::iterator_traits<TIter>::value_type;
  std::vector<TValue> addMemory(dist);

  for (size_t step = 1; step < dist; step *= 2)
  {
    for (size_t lower = 0; lower < dist - step; lower += step << 1)
    {
      TIter s = iter::NextIter(beg, lower);
      TIter m = iter::NextIter(s, step);
      size_t upperOffset = step << 1;
      if (lower + upperOffset > dist)
        upperOffset = dist - lower;

      TIter e = iter::NextIter(s, upperOffset);
      impl::Merge(iter::NextIter(addMemory.begin(), lower), s, m, m, e);
    }

    std::copy(addMemory.begin(), addMemory.end(), beg);
  }
}

} // namespace sort