隨機化算法之隨機數

首先是介紹：

代碼如下：

//隨機數類
//Random.hpp
//=====================================================
#ifndef RANDOM_HPP
#define RANDOM_HPP

#include<ctime>

const unsigned long maxshort = 65536L;
const unsigned long multiplier = 1194211693L;
const unsigned long adder = 12345L;

class RandomNumber{
private:
    //當前種子
    unsigned long randSeed;
public:
    RandomNumber(){};
    RandomNumber(unsigned long s = 0);  //構造函數,默認值0表示由系統自動產生種子
    unsigned short Random(unsigned long n);  //產生0:n-1之間的隨機整數
    double fRandom(void);  //產生[0 , 1)之間的隨機整數
};

RandomNumber::RandomNumber(unsigned long s)  //產生種子
{
    if (s == 0)
    {
        randSeed = time(0);  //使用系統時間產生隨機種子
    }
    else
    {
        randSeed = s;
    }
}

unsigned short RandomNumber::Random(unsigned long n)  //產生 0:n-1之間的隨機整數
{
    randSeed = multiplier * randSeed + adder;
    return(unsigned short)((randSeed >> 16) % n);
}

double RandomNumber::fRandom(void)  //產生[0 , 1)之間的隨機數
{
    return Random(maxshort) / double(maxshort);
}

#endif

 

//隨機數
//main.cpp
//==============================================
#include <iostream>
#include <iomanip>
#include "Random.hpp"

using namespace std;

int TossCoins(int numberCoins)
{
    //隨機拋硬幣
    static RandomNumber coinToss(0);
    int tosses = 0;
    for (int i = 0; i < numberCoins; i++)
    {
        tosses += coinToss.Random(2);
    }
    return tosses;
}

int main(void)
{
    //模擬隨機拋硬幣事件
    const int NCOINS = 10;
    const long NTOSSES = 50000L;
    //heads[i]是得到i次正面的次數
    long heads[NCOINS + 1];
    int position;
    //初始化數組heads
    for (int i = 0; i < NCOINS + 1; i++)
    {
        heads[i] = 0;
    }
    //重復50000次試驗
    for (int j = 0; j < NTOSSES; j++)
    {
        heads[TossCoins(NCOINS)] ++;
    }
    //輸出頻率圖
    for (int i = 0; i < NCOINS; i++)
    {
        position = int(float(heads[i]) / NTOSSES * 72);
        cout << setw(6) << i << " ";
        for (int j = 0; j < position - 1; j++)
        {
            cout << " ";
        }
        cout << "*" << endl;
    }

    system("pause");
}

 結果如下（頻率圖）：