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  1. #include <iostream>
  2. #include <random>
  3. #include <numeric>
  4. #include <iterator>
  5.  
  6. // seed the generator
  7. std::mt19937 generator((std::random_device())());
  8.  
  9. struct DieInterface
  10. {
  11.     virtual ~DieInterface() = default;
  12.     virtual unsigned operator()() const = 0 ;
  13.     virtual unsigned sides() const = 0;
  14. };
  15.  
  16. struct Die : public DieInterface
  17. {
  18.     Die(unsigned nSides) : _dist(1, nSides) {}
  19.  
  20.     unsigned operator()() const { return _dist(generator); }
  21.     unsigned sides() const { return _dist.b(); }
  22.  
  23. private:
  24.     mutable std::uniform_int_distribution<unsigned> _dist;
  25. };
  26.  
  27. struct LoadedDie : public DieInterface
  28. {
  29.     using distribution = std::uniform_int_distribution<unsigned>;
  30.  
  31.     LoadedDie(unsigned nSides, unsigned loadedFace, unsigned weight_out_of_100)
  32.         : _dist(1, nSides - 1), _face(loadedFace), _weight(weight_out_of_100) {}
  33.  
  34.     unsigned operator()() const
  35.     {
  36.         using param_type = distribution::param_type;
  37.  
  38.         if (_dist(generator, param_type{ 1, 100 }) >= _weight)
  39.             return _face;
  40.         else
  41.         {
  42.             unsigned face = _dist(generator);
  43.  
  44.             if (face >= _face)
  45.                 ++face;
  46.  
  47.             return face;
  48.         }
  49.     }
  50.  
  51.     unsigned sides() const { return _dist.b() + 1; }
  52.  
  53. private:
  54.     mutable distribution _dist;
  55.  
  56.     unsigned _face;
  57.     unsigned _weight;
  58. };
  59.  
  60.  
  61. // Take two dice objects, roll them, and return the sum
  62.  
  63. template <typename iter_type>
  64. unsigned roll(iter_type beg, iter_type end)
  65. {
  66.     using die_type = const DieInterface&;
  67.     return std::accumulate(beg, end, 0u, [](unsigned x, die_type d) { return x + d(); });
  68. }
  69.  
  70. int main()
  71. {
  72.     Die dice[] = { Die(6), Die(10) };
  73.  
  74.     std::cout << "\nRolling two normal dice:\n";
  75.     for (int i = 0; i < 10; ++i)
  76.         std::cout << roll(std::begin(dice), std::end(dice)) << '\n';
  77.  
  78.     {
  79.         const unsigned faces = 6;
  80.         const unsigned loaded_face = 6;
  81.         const unsigned weight = 50;
  82.  
  83.         LoadedDie die(faces, loaded_face, weight);
  84.  
  85.         std::cout << "\n\nRolling the loaded die with a 50 percent chance to roll max val:\n";
  86.         for (int i = 0; i < 10; ++i)
  87.             std::cout << die() << '\n';
  88.     }
  89.  
  90.     {
  91.         const unsigned faces = 20;
  92.         const unsigned loaded_face = 5;
  93.         const unsigned weight = 50;
  94.  
  95.         LoadedDie die(faces, loaded_face, weight);
  96.  
  97.         std::cout << "\n\nRolling a 20-sided loaded die: (" << loaded_face << "is loaded)\n";
  98.         for (int i = 0; i < 10; ++i)
  99.             std::cout << die() << '\n';
  100.     }
  101. }
Success #stdin #stdout 0s 3432KB
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stdin
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Standard input is empty
stdout
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Rolling two normal dice:
9
12
11
11
9
9
8
9
13
9


Rolling the loaded die with a 50 percent chance to roll max val:
6
2
6
6
5
4
6
5
1
2


Rolling a 20-sided loaded die: (5is loaded)
5
5
14
3
5
20
10
13
18
5
https://ideone.com/g6rmXt
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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