Random Number Generator
(utility/random_number_generator.hpp)

• View this file on GitHub
• Last update: 2023-12-26 02:24:03+09:00
• Include: #include "utility/random_number_generator.hpp"

説明

整数の乱数生成機。

set_seed(seed)

シードを指定する。

get(a, b)

$[a, b)$ の範囲から一様乱数を生成する。

Required by

• Rolling Hash (string/rolling_hash.hpp)
• Rooted Tree Hash (tree/rooted_tree_hash.hpp)
• Hash structure (utility/hash.hpp)

Verified with

• test/aoj/aoj_2444.test.cpp
• test/data_structure/Range_Parallel_DSU.test.cpp
• test/tree/Rooted_Tree_Isomorphism_Classification.test.cpp

Code

#pragma once

#include <cstdint>

#include <random>


namespace ebi {

struct random_number_generator {
    random_number_generator(int seed = -1) {
        if (seed < 0) seed = rnd();
        mt.seed(seed);
    }

    void set_seed(int seed) {
        mt.seed(seed);
    }

    template <class T> T get(T a, T b) {
        std::uniform_int_distribution<T> dist(a, b - 1);
        return dist(mt);
    }

  private:
    std::mt19937_64 mt;
    std::random_device rnd;
};

}  // namespace ebi

#line 2 "utility/random_number_generator.hpp"

#include <cstdint>

#include <random>


namespace ebi {

struct random_number_generator {
    random_number_generator(int seed = -1) {
        if (seed < 0) seed = rnd();
        mt.seed(seed);
    }

    void set_seed(int seed) {
        mt.seed(seed);
    }

    template <class T> T get(T a, T b) {
        std::uniform_int_distribution<T> dist(a, b - 1);
        return dist(mt);
    }

  private:
    std::mt19937_64 mt;
    std::random_device rnd;
};

}  // namespace ebi

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