C++抛硬币程序

Question

我试图编写一个 C++ 程序来计算我连续抛掷了多少次相同类型的硬币，但结果很奇怪。我试着扔了 1,000,000 次，但我没有得到比 15 次更多的“相同类型的连续抛掷”。我用较少的抛掷次数 (5-20) 测试了它，它似乎工作正常，除了我也没有连续获得超过 15 个相同类型。

#include <iostream>
#include <ctime>

#define LOOP 1000000//how many times do I toss a coin

int main()
{
int maxTails = 0, maxHeads = 0, currentTails = 0, currentHeads = 0, totalHeads = 0, totalTails = 0;

int totalMax = 0;//highest amount of "in a row" out of all iterations

bool heads = false;//last toss

srand(time(0));

for (int x = 0; x < 100; ++x) {//this is to increase the amount of how many times I want to toss a coin LOOP times
    for (int i = 0; i < LOOP; ++i)//tosses a coin LOOP times
    {
        if (rand() % 2 == 0)// heads
        {
            if (heads == false)//if last toss was tails I check if the "in a row" for it was more than the current maximum
            {
                if (currentTails > maxTails) maxTails = currentTails;
                currentTails = 0;
                currentHeads = 0;
                heads = true;
            }
            currentHeads++;
            totalHeads++;
            if (currentHeads > maxHeads) maxHeads = currentHeads;
        }
        else//tails
        {
            if (heads == true)
            {
                if (currentHeads > maxHeads) maxHeads = currentHeads;
                currentHeads = 0;
                currentTails = 0;
                heads = false;
            }
            currentTails++;
            totalTails++;
            if (currentTails > maxTails) maxTails = currentTails;
        }
    }

    if (maxTails > totalMax) totalMax = maxTails;//totalMax is the maximum "in a row" of either tails or heads
    if (maxHeads > totalMax) totalMax = maxHeads;

    std::cout << "Throws: " << LOOP << ", Total heads: " << totalHeads << ", Total tails: " << totalTails << ", Maximum heads: " << maxHeads << ", Maximum tails: " << maxTails << std::endl;//writes all the info
    //std::cout << "Iteration: " << x + 1 << ", Max: " << totalMax << std::endl;
    maxTails = maxHeads = currentHeads = currentTails = totalHeads = totalTails = 0;
}
std::cout << "Max: " << totalMax << std::endl;

system("pause");
return 0;
}

我在互联网上读到，如果您抛硬币 1,000,000 次，连续获得 20 次正面朝上的概率约为 38%，但我的程序运行方式不同。我的代码有问题还是 rand() 函数有问题？

Answer 1

阅读@BathSheba 评论。期望与您现在得到的不同的输出是不准确的。

为了简单起见以便读者可以根据需要进行调试，这是您的代码的工作版本:

#include <iostream>
#include <ctime>

#define LOOP 1000000 //how many times do I toss a coin

int main()
{
    int maxTails = 0;
    int maxHeads = 0;
    int currentTotalTails = 0; 
    int currentTotalHeads = 0;

    srand(time(NULL));

    for (int i = 0; i < LOOP; ++i) //tosses a coin LOOP times
    {
        if (rand() % 2 == 0)// heads
        {
            currentTotalHeads++;
            currentTotalTails = 0;

            if (currentTotalHeads > maxHeads)
                maxHeads = currentTotalHeads;

        }
        else // tails
        {
            currentTotalTails++;
            currentTotalHeads = 0;

            if (currentTotalTails > maxTails)
                maxTails = currentTotalTails;
        }
    }

    std::cout << "Max Heads in a row: " << maxHeads << std::endl;
    std::cout << "Max Tails in a row: " << maxTails << std::endl;

    system("pause");
    return 0;
}