bitonic sort代码

以下是Bitonic sort的Python代码：

def bitonic_sort(a):
    if len(a) <= 1:
        return a
    else:
        # sort the first half in ascending order
        first_half = bitonic_sort(a[:len(a)//2])
        # sort the second half in descending order
        second_half = bitonic_sort(a[len(a)//2:])[::-1]
        # combine the two halves in ascending order
        return bitonic_merge(first_half + second_half)

def bitonic_merge(a):
    if len(a) <= 1:
        return a
    else:
        # split the array into two halves
        mid = len(a) // 2
        # make sure the two halves are of equal length
        if len(a) % 2 != 0:
            mid += 1
        # sort the first half in ascending order
        first_half = bitonic_merge(a[:mid])
        # sort the second half in descending order
        second_half = bitonic_merge(a[mid:])[::-1]
        # merge the two halves in ascending order
        return bitonic_compare(first_half + second_half)

def bitonic_compare(a):
    if len(a) <= 1:
        return a
    else:
        # compare and swap adjacent elements
        for i in range(0, len(a)//2):
            if a[i] > a[i+len(a)//2]:
                a[i], a[i+len(a)//2] = a[i+len(a)//2], a[i]
        # recursively compare and swap the two halves
        first_half = bitonic_compare(a[:len(a)//2])
        second_half = bitonic_compare(a[len(a)//2:])
        return first_half + second_half

该算法的时间复杂度为O(n log^2 n)，空间复杂度为O(n)。