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std::discrete_distribution(3)  C++ Standard Libary std::discrete_distribution(3)

NAME
     std::discrete_distribution - std::discrete_distribution

Synopsis
	Defined in header <random>
	template< class IntType = int >  (since C++11)
	class discrete_distribution;

	std::discrete_distribution  produces random integers on the interval [0,
     n), where
	the probability of each individual integer i is defined as w
	i/S, that is the weight of the ith integer divided by the sum of  all  n
     weights.

	std::discrete_distribution  satisfies  all  requirements  of  RandomNum-
     berDistribution.

Template parameters
		  The result type generated by the generator. The effect is  un-
     defined if
	IntType  -  this  is  not  one	of short, int, long, long long, unsigned
     short, unsigned
		  int, unsigned long, or unsigned long long.

Member types
	Member type	    Definition
	result_type (C++11) IntType
	param_type (C++11)  the type of the parameter set, see	RandomNumberDis-
     tribution.

Member functions
	constructor   constructs new distribution
	(C++11)       (public member function)
	reset	      resets the internal state of the distribution
	(C++11)       (public member function)

Generation
	operator()    generates the next random number in the distribution
	(C++11)       (public member function)

Characteristics
	probabilities obtains the list of probabilities
		      (public member function)
	param	      gets or sets the distribution parameter object
	(C++11)       (public member function)
	min	      returns the minimum potentially generated value
	(C++11)       (public member function)
	max	      returns the maximum potentially generated value
	(C++11)       (public member function)

Non-member functions
	operator==
	operator!=		  compares two distribution objects
	(C++11) 		  (function)
	(C++11)(removed in C++20)
	operator<<		   performs  stream  input and output on pseudo-
     random number
	operator>>		  distribution
	(C++11) 		  (function template)

Example
     // Run this code

      #include <iomanip>
      #include <iostream>
      #include <map>
      #include <random>

      int main()
      {
	  std::random_device rd;
	  std::mt19937 gen(rd());
	  std::discrete_distribution<> d({40, 10, 10, 40});
	  std::map<int, int> map;

	  for (int n = 0; n < 1e4; ++n)
	      ++map[d(gen)];

	  for (const auto& [num, count] : map)
	      std::cout << num << " generated " << std::setw(4) <<  count  <<  "
     times\n";
      }

Possible output:
      0 generated 4037 times
      1 generated  962 times
      2 generated 1030 times
      3 generated 3971 times

http://cppreference.com 	   2024.06.10	   std::discrete_distribution(3)
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