python - 为什么我的 Monty Hall 解决方案不起作用？

Question

下面的代码是我的实现(Python 3.3.1)，看看我能否证明开关在蒙提霍尔问题中是有效的。当我让玩家保留他们的第一选择时，我大致得到大约 0.33 的正确猜测结果，这是预期的。当我切换播放器时会出现问题 - 而不是获得预期的 ~0.66，我始终得到 ~0.55。

任何人都可以看到错误吗？ (另外，作为旁注，如果我能对代码做出任何改进，我们将不胜感激)

def runInstance(switch): #run a single Monty Hall Problem instance
    choicesList = [False,False,False]
    intTruth = randint(0,2)
    choicesList[intTruth] = True #list has been set up with 2 False, 1 True
    intChoice = randint(0,2)
    for index in range(0,len(choicesList)): #Loop finds entry index which is not chosen and is False to "present" to player
        if( (intChoice != index) and (choicesList[index] == False) ):
            alternate = index
    if(switch):
        for index in range(0,len(choicesList)): #Loop finds entry index which hasn't been chosen, and isn't the "Opened Door", then switches to it
            if( (index != intChoice) and (index != alternate) ):
                intChoice = index
    return choicesList[intChoice]

def runBatch(inputSize, switch): #Run batch of instances for stats
    successCount = 0.0
    for index in range(0,int(inputSize)):
        if(runInstance(switch)):
            successCount += 1.0
    print(str(successCount/inputSize))

runBatch(100000.0, True) #Number of instances to run, and boolean indicating whether to switch

Answer 1

将代码更改为:

origChoice = intChoice
if(switch):
    for index in range(0,len(choicesList)): #Loop finds entry index which hasn't been chosen, and isn't the "Opened Door", then switches to it
        if( (index != origChoice) and (index != alternate) ):
            intChoice = index

问题是有时你会切换然后又切换回原来的选择。

换句话说，如果 intChoice=2,alternate=1 那么:

1. 在第一次交互时 intChoice 将变为 0
2. 在第二次迭代中什么也不会发生(因为 index==alternate)
3. 在第三次迭代时 intChoice 将变回 2