我正在尝试编写一个将整数列表作为输入并输出反转次数的反转计数器。由于它将处理大型列表，因此我使用了分而治之递归方法，但出现以下错误:

Traceback (most recent call last):
  File "C:\Users\Jonathan\Desktop\py.py", line 34, in <module>
    Inversions([1,2,3,4,5], 5)
  File "C:\Users\Jonathan\Desktop\py.py", line 13, in Inversions
    x = Inversions(numbers[:length/2 - 0.5], length/2-0.5)
TypeError: slice indices must be integers or None or have an __index__ method

def Inversions(numbers, length):
    if length == 0:
        return 0
    else:
        if length%2 == 0:
            x = Inversions(numbers[:length/2], length/2)
            y = Inversions(numbers[length/2:], length/2)
            b = sorted(numbers[:length/2], length/2)
            c = sorted(numbers[length/2:], length/2)
            z = Split(b, c)
            return x+y+z
        elif length%2 == 1:
            x = Inversions(numbers[:length/2 - 0.5], length/2-0.5)
            y = Inversions(numbers[length/2 - 0.5:], length/2-0.5)
            b = sorted(numbers[:length/2 - 0.5], length/2-0.5)
            c = sorted(numbers[length/2 - 0.5:], length/2-0.5)
            z = Split(b, c)
            return x+y+z
def Split(first, second):
    i = 1
    j = 1
    d = []
    inversions = 0
    for k in range(1,len(b)+1):
        if b[i] < C[j]:
            d[k] = b[i]
            i += 1
        else:
            d[k] = c[j]
            inversions += len(b[i:])
            j += 1
    return inversions

Inversions([1,2,3,4,5], 5)

最佳答案

length是偶数，这将导致非整数浮点数。请改用整数除法。

x = Inversions(numbers[:length // 2], length // 2)

https://stackoverflow.com/questions/18140921/