Python If/else 混淆

Question

所以我的游戏有问题，我从这里复制粘贴了一部分。正如您所看到的，只有当列表位置的前 x 个元素小于 7 并且所有其余元素都大于 7 并且最后一个元素为 0 时，此代码才会打印 Yeah。但是，正如您在示例中看到的， 0 不是列表中的最后一个元素，但我得到了打印是的。为什么？谢谢你！

position=[3,6,4,2,5,0,10,12,7,8]

where=1

a=1

for i in range(6-where):

    if position[i]<7 and position[i]!=0:

        pass

    else:

        a=0

print(a)

for i in range(6-where,-1):

    if position[i]>6 and position[-1]==0:

        pass

    else:

        a=0

print(a)

print(position[-1])

if a==1:

    print("Yeah")

Answer 1

您可以选择将其放入函数中吗？如果是这样，尽早退出是你的朋友：def is_winner(nums, middle):&nbsp; &nbsp; # The last number must be a zero&nbsp; &nbsp; if nums[-1] != 0:&nbsp; &nbsp; &nbsp; &nbsp; return False&nbsp; &nbsp; # All of the starting numbers must be less than 7&nbsp; &nbsp; if not all(num < 7 for num in nums[:middle]):&nbsp; &nbsp; &nbsp; &nbsp; return False&nbsp; &nbsp; # All of the ending numbers must be at least 7&nbsp; &nbsp; if not all(num >= 7 for num in nums[middle:-1]):&nbsp; &nbsp; &nbsp; &nbsp; return False&nbsp; &nbsp; # If all of those are OK, then we've succeeded&nbsp; &nbsp; return True# This will print False because it doesn't end in 0.position = [3, 6, 4, 2, 5, 0, 10, 12, 7, 8]print(is_winner(position, 6))# This will print True because it meets the requirements.position = [3, 6, 4, 2, 5, 0, 10, 12, 7, 8, 0]print(is_winner(position, 6))# This will print False because a number in the first part is greater than 7position = [3, 6, 4, 2, 5, 0, 10, 12, 7, 8, 0]print(is_winner(position, 7))# This will print False because a number in the second part is not at least 7position = [3, 6, 4, 2, 5, 0, 10, 12, 7, 8, 0]print(is_winner(position, 5))看看这个函数如何变得非常简单和可读？在每一步中，如果不满足要求，您就会停止。您不必跟踪状态或任何东西；你只需返回 False 即可。如果您到达函数末尾并且没有失败任何测试，那么 ta-da！您成功了并且可以返回 True。顺便说一句，根据你的例子，第二个要求应该是x >= 7，而不是x > 7。如果不正确，请更新代码和示例以匹配。

Answer 2

您的代码中可能有两个错误：第一个if语句中的行必须是 if position[i]<7 and position[-1]!=0:，但您已经编写了... and position[i]!=0其次，您的第二个 for 循环不会被执行，因为它的iterator 是range(6-where,-1)， range 函数默认给出一个升序迭代器，所以在你的情况下迭代器是空的。对于降序列表，请向range func 添加一个step参数并使用。 这里最后一个-1是范围函数的步长range(6-where, -1, -1)

Answer 3

你的代码看起来有点纠结。首先，使用布尔值和适当的名称a。例如listValid = True。但没有它也是可能的。position=[3,6,4,2,5,0,10,12,7,8]splitIndex = 6 - 1if all([value < 7 for value in position[:splitIndex]]):&nbsp; &nbsp; &nbsp;if all([value > 6 for value in position[splitIndex:-1]]):&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if position[-1] == 0:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;print("Yeah")

Answer 4

在第一个 if 语句中，您有位置 [i] 而不是位置 [-1]。这里还有一些改进的、更简单的代码：position=[3,6,4,2,5,0,10,12,7,8]x = 5valid_list = Truefor i in range(x):&nbsp; &nbsp; if position[i] >= 7 or position[i] == 0:&nbsp; &nbsp; &nbsp; &nbsp; valid_list = Falsefor i in range(len(position) - x - 1):&nbsp; &nbsp; if position[x + i] < 7 or position[i] == 0:&nbsp; &nbsp; &nbsp; &nbsp; valid_list = False&nbsp; &nbsp; &nbsp; &nbsp;&nbsp;if valid_list and position[-1] == 0:&nbsp; &nbsp; print('Yeah')