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  1. // implementation:
  2. #include <time.h>
  3. #include <algorithm>
  4. #include <array>
  5. #include <numeric>
  6. #include <random>
  7. #include <vector>
  8.  
  9. std::array<std::array<int, 4>, 4> make_random_array()
  10. {
  11.     typedef std::vector<int>::difference_type diff_t;
  12.  
  13.     std::array<std::array<int, 4>, 4> ret;
  14.     std::vector<int> v(16);
  15.     std::iota(v.begin(), v.end(), 0);
  16.     std::mt19937 prng(static_cast<std::mt19937::result_type>(time(0)));
  17.     auto shuffler = [&prng](diff_t const n)
  18.     {
  19.         return std::uniform_int_distribution<diff_t>(0, n + 1)(prng);
  20.     };
  21.     std::random_shuffle(v.begin(), v.end(), shuffler);
  22.     for (decltype(v.size()) i = 0, i_end = v.size(); i != i_end; ++i)
  23.         ret[i / 4][i % 4] = v[i];
  24.     return ret;
  25. }
  26.  
  27. //example usage:
  28. #include <iomanip>
  29. #include <iostream>
  30.  
  31. int main()
  32. {
  33.     auto const arr = make_random_array();
  34.     std::for_each(
  35.         arr.cbegin(), arr.cend(), [](std::array<int, 4> const& o)
  36.         {
  37.             std::for_each(
  38.                 o.cbegin(), o.cend(), [](int const i)
  39.                 {
  40.                     std::cout << std::setw(2) << i << ' ';
  41.                 }
  42.             );
  43.             std::cout << '\n';
  44.         }
  45.     );
  46. }
Success #stdin #stdout 0s 3060KB
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stdin
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Standard input is empty
stdout
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12 11 14  7 
13 15  0  2 
 5  9 10  4 
 1  8  3  6
https://ideone.com/48OPe
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
secret

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