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std::discrete_distribution(3) C++ Standard Libarystd::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
       undefined 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	    IntType
	  param_type(C++11)  the  type	of  the	 parameter set,	see RandomNum-
       berDistribution.

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 <iostream>
	#include <iomanip>
	#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<10000; ++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		  2022.07.31	 std::discrete_distribution(3)

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