乱数生成
(random/rng.hpp)

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• Last update: 2025-03-09 11:07:17+09:00
• Include: #include "random/rng.hpp"

Required by

• 木ハッシュ (graph/tree/tree-hash.hpp)

Verified with

• test/aoj/aoj2821.test.cpp
• test/mytest/data-structure/binary-trie.test.cpp
• test/mytest/misc/fraction.test.cpp

Code

#pragma once

#include <chrono>
#include <random>

class RNG32 {
  public:
    RNG32() : mt(std::chrono::steady_clock::now().time_since_epoch().count()) {}
    // [l, r)
    int randint(int l, int r) {
        std::uniform_int_distribution<int> dist(l, r - 1);
        return dist(mt);
    }
    int randint(int r) { return randint(0, r); }

  private:
    std::mt19937 mt;
};

class RNG64 {
  public:
    RNG64() : mt(std::chrono::steady_clock::now().time_since_epoch().count()) {}
    // [l, r)
    long long randint(long long l, long long r) {
        std::uniform_int_distribution<long long> dist(l, r - 1);
        return dist(mt);
    }
    long long randint(long long r) { return randint(0, r); }

  private:
    std::mt19937_64 mt;
};

class RNG_0_1 {
  public:
    RNG_0_1() : mt(std::chrono::steady_clock::now().time_since_epoch().count()) {}

    // [0.0, 1.0)
    double rand() {
      auto bits = mt() >> 11;
      return (double)bits / denomitor;
    }

    auto operator()() { return rand(); }

  private:
    std::mt19937_64 mt;
    const double denomitor = 1LL << 53;
};

#line 2 "random/rng.hpp"

#include <chrono>
#include <random>

class RNG32 {
  public:
    RNG32() : mt(std::chrono::steady_clock::now().time_since_epoch().count()) {}
    // [l, r)
    int randint(int l, int r) {
        std::uniform_int_distribution<int> dist(l, r - 1);
        return dist(mt);
    }
    int randint(int r) { return randint(0, r); }

  private:
    std::mt19937 mt;
};

class RNG64 {
  public:
    RNG64() : mt(std::chrono::steady_clock::now().time_since_epoch().count()) {}
    // [l, r)
    long long randint(long long l, long long r) {
        std::uniform_int_distribution<long long> dist(l, r - 1);
        return dist(mt);
    }
    long long randint(long long r) { return randint(0, r); }

  private:
    std::mt19937_64 mt;
};

class RNG_0_1 {
  public:
    RNG_0_1() : mt(std::chrono::steady_clock::now().time_since_epoch().count()) {}

    // [0.0, 1.0)
    double rand() {
      auto bits = mt() >> 11;
      return (double)bits / denomitor;
    }

    auto operator()() { return rand(); }

  private:
    std::mt19937_64 mt;
    const double denomitor = 1LL << 53;
};

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