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  1. #include <algorithm>
  2. #include <functional>
  3. #include <iostream>
  4. #include <iterator>
  5.  
  6. template<class BiDirIt, class Compare = std::less<>>
  7. void merge_sort(BiDirIt first, BiDirIt last, Compare cmp = Compare{})
  8. {
  9.     auto const N = std::distance(first, last);
  10.     if (N <= 1) return;
  11.     auto const middle = std::next(first, N / 2);
  12.     merge_sort(first, middle, cmp); // assert(std::is_sorted(first, middle, cmp));
  13.     merge_sort(middle, last, cmp);  // assert(std::is_sorted(middle, last, cmp));
  14.     std::inplace_merge(first, middle, last, cmp); // assert(std::is_sorted(first, last, cmp));
  15. }
  16.  
  17. class int_buffer {
  18. public:
  19.     explicit int_buffer(size_t size); // size_t is defined in cstdlib
  20.     int_buffer(const int* source, size_t size);
  21.     int_buffer(const int_buffer& rhs); // copy construct
  22.     int_buffer(int_buffer&& rhs); // move construct
  23.     int_buffer & operator=(const int_buffer& rhs); // copy assign
  24.     int_buffer & operator=(int_buffer&& rhs); // move assign
  25.     size_t size() const;
  26.     int* begin();
  27.     int* end();
  28.     const int* begin() const;
  29.     const int* end() const;
  30.     ~int_buffer();
  31. private:
  32.     int* buffer;
  33.     size_t bufferSize;
  34. };
  35.  
  36. int_buffer::int_buffer(size_t size) :buffer(new int[size]), bufferSize(size) {
  37. }
  38.  
  39. int_buffer::int_buffer(const int* source, size_t size) : buffer(new int[size]), bufferSize(size) {
  40.     for (int i = 0; i < size; i++) {
  41.         buffer[i] = source[i];
  42.     }
  43. }
  44.  
  45. int_buffer::int_buffer(const int_buffer& rhs) :buffer(new int[rhs.size()]), bufferSize(rhs.size()) {
  46.     std::copy(rhs.begin(), rhs.end(), begin());
  47. }
  48.  
  49. int_buffer::int_buffer(int_buffer&& rhs) {
  50.     buffer = rhs.buffer;
  51.     bufferSize = rhs.size();
  52.     rhs.buffer = nullptr;
  53. }
  54.  
  55. int_buffer& int_buffer::operator=(const int_buffer& rhs) {
  56.     if (buffer == rhs.begin()) {
  57.         return *this;
  58.     }
  59.     else if (bufferSize == rhs.size()) {
  60.         std::copy(rhs.begin(), rhs.end(), begin());
  61.         return *this;
  62.     }
  63.     else {
  64.         delete[]buffer;
  65.         buffer = new int[rhs.size()];
  66.         bufferSize = rhs.size();
  67.         std::copy(rhs.begin(), rhs.end(), begin());
  68.         return *this;
  69.     }
  70.     return *this;
  71. }
  72.  
  73. int_buffer& int_buffer::operator=(int_buffer&& rhs) {
  74.     if (this != &rhs) {
  75.         delete[]buffer;
  76.         this->buffer = rhs.buffer;
  77.         rhs.buffer = nullptr;
  78.     }
  79.     return *this;
  80. }
  81.  
  82.  
  83. size_t int_buffer::size() const {
  84.     return bufferSize;
  85. }
  86.  
  87. int* int_buffer::begin() {
  88.     return buffer;
  89. }
  90.  
  91. int* int_buffer::end() {
  92.     return buffer + bufferSize;
  93. }
  94.  
  95. const int* int_buffer::begin() const {
  96.     return buffer;
  97. }
  98.  
  99. const int* int_buffer::end() const {
  100.     return buffer + bufferSize;
  101. }
  102.  
  103. int_buffer::~int_buffer() {
  104.     delete[]buffer;
  105. }
  106.  
  107. using namespace std;
  108. void fill(int_buffer &buffer);
  109.  
  110. int main(int argc, const char * argv[]) {
  111.     int_buffer buffer(10);
  112.     fill(buffer);
  113.     merge_sort(buffer.begin(), buffer.end());
  114.     std::cout << "\n";
  115.     std::copy(buffer.begin(), buffer.end(), std::ostream_iterator<int>(std::cout, " "));
  116.  
  117.     return 0;
  118. }
  119.  
  120. void fill(int_buffer &buffer) {
  121.     int value = 0;
  122.     for (int *i = buffer.begin(); i != buffer.end(); i++) {
  123.         value = rand() % 10;
  124.         *i = value;
  125.     }
  126.  
  127.     for (const int* i = buffer.begin(); i != buffer.end(); i++) {
  128.         std::cout << *i << std::endl;
  129.     }
  130. }
  131.  
Success #stdin #stdout 0s 15240KB
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https://ideone.com/FN6x47
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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