rng.h

#ifndef UTILS_RNG_H
#define UTILS_RNG_H
 
#include <algorithm>
#include <cassert>
#include <random>
#include <vector>
 
namespace utils {
class RandomNumberGenerator {
    // Mersenne Twister random number generator.
    std::mt19937 rng;
 
public:
    RandomNumberGenerator(); // Seed with a value depending on time and process
                             // ID.
    explicit RandomNumberGenerator(int seed);
    RandomNumberGenerator(const RandomNumberGenerator&) = delete;
    RandomNumberGenerator& operator=(const RandomNumberGenerator&) = delete;
    ~RandomNumberGenerator();
 
    void seed(int seed);
 
    // Return random double in [0..1).
    double random()
    {
        std::uniform_real_distribution<double> distribution(0.0, 1.0);
        return distribution(rng);
    }
 
    // Return random integer in [0..bound).
    int random(int bound)
    {
        assert(bound > 0);
        std::uniform_int_distribution<int> distribution(0, bound - 1);
        return distribution(rng);
    }
 
    template <typename T>
    typename T::const_iterator choose(const T& vec)
    {
        return vec.begin() + random(vec.size());
    }
 
    template <typename T>
    typename T::iterator choose(T& vec)
    {
        return vec.begin() + random(vec.size());
    }
 
    template<typename T>
    void shuffle(std::vector<T>& vec)
    {
        std::shuffle(vec.begin(), vec.end(), rng);
    }
};
} // namespace utils
 
#endif