二进制搜索迭代和递归元组（python）

我正在尝试创建一个二进制搜索，包括迭代搜索和递归搜索，参数为tuple，int。我真的很想了解它，因为我认为我在逻辑上理解了代码，但显然不是这样

迭代代码isMemberI在一半的时间里给出了正确的结果，然后随机地给出了错误的结果，所以我不知道是什么导致了这种情况。我没有错，只是有时候回答错了

递归代码有时会给我错误，然后在我的测试用例中可能有¼个可以工作。当我尝试以下操作时，会出现以下错误：

>>> isMemberR((1, 2, 3, 3, 4), 4
Traceback (most recent call last):
  File "<pyshell#0>", line 1, in <module>
    isMemberR((1, 2, 3, 3, 4), 4)
  File "/Users/alyssakelley/Documents/p93_binsearch.py", line 127, in     isMemberR
    return isMemberR(aseq[midpoint + 1], target)
  File "/Users/alyssakelley/Documents/p93_binsearch.py", line 117, in isMemberR
    if len(aseq) == 0:
TypeError: object of type 'int' has no len()

>>> isMemberR('aeiou', 'y')
Traceback (most recent call last):
  File "<pyshell#3>", line 1, in <module>
    isMemberR('aeiou', 'y')
  File "/Users/alyssakelley/Documents/p93_binsearch.py", line 127, in isMemberR
    return isMemberR(aseq[midpoint + 1], target)
  File "/Users/alyssakelley/Documents/p93_binsearch.py", line 127, in isMemberR
    return isMemberR(aseq[midpoint + 1], target)
IndexError: string index out of range


>>> isMemberR((1, 3, 5, 7), 4)
Traceback (most recent call last):
  File "<pyshell#4>", line 1, in <module>
    isMemberR((1, 3, 5, 7), 4)
  File "/Users/alyssakelley/Documents/p93_binsearch.py", line 125, in isMemberR
    return isMemberR(aseq[:midpoint], target)
  File "/Users/alyssakelley/Documents/p93_binsearch.py", line 127, in isMemberR
   return isMemberR(aseq[midpoint + 1], target)
IndexError: tuple index out of range

---

这里最后一个函数调用是在索引中点+1处传递一个值，而不是元组

错误解释

索引器错误：元组索引超出范围，当元组的len为1且中点+1为1时会发生这种情况，因为只有一个元素超出范围

TypeError：“int”类型的对象没有len，这是在最后一行将int作为第一个参数传递给IsMember时

---

isMemberRaseq[Middpoint+1]中的aseq[Middpoint+1]是否为目标ASEQUE？不是，太棒了！！谢谢你解释：D

def isMemberI(aseq, target):
    first = 0
    last = len(aseq) - 1
    found = False

    while first < last:
        midpoint = (first + last) // 2
        if aseq[midpoint] == target:
            found = True

        else:
            if target < aseq[midpoint]:
                last = midpoint - 1
            else:
                first = midpoint + 1
    return found 

def isMemberR(aseq, target):
    if len(aseq) == 0:
        return False
    else:
        midpoint = len(aseq) // 2
        if aseq[midpoint] == target:
            return True
        else:
            if target < aseq[midpoint]:
                return isMemberR(aseq[:midpoint], target)
            else:
                return isMemberR(aseq[midpoint + 1], target)

>>> isMemberI((1, 2, 3, 3, 4), 4)
True

>>> isMemberI((1, 2, 3, 3, 4), 2)
True

>>> isMemberI('aeiou', 'i')
True

>>> isMemberI('aeiou', 'y')
False

>>> isMemberI((1, 3, 5, 7), 4)
False

>>> isMemberI((23, 24, 25, 26, 27), 5)
False

>>> isMemberI((0, 1, 4, 5, 6, 8), 4)
True

>>> isMemberI((0, 1, 2, 3, 4, 5, 6), 3)
True

>>> isMemberI((1, 3), 1)
True

>>> isMemberI((2, 10), 10)
True

>>> isMemberI((99, 100), 101)
False

>>> isMemberI((42,), 42)
True

>>> isMemberI((43,), 44)
False

>>> isMemberI((), 99)
False
'''

def isMemberR(aseq, target):
    if len(aseq) == 0:
        return False
    else:
        midpoint = len(aseq) // 2
        if aseq[midpoint] == target:
            return True
        else:
            if target < aseq[midpoint]:
                return isMemberR(aseq[:midpoint], target)
            else:
                return isMemberR(aseq[midpoint+1:], target)