leetcode--快速排序

def quick_sort(alist, start, end):
    if start >= end:
        return None

    left, right = start, end
    value = alist[left]
    while left < right:
        # [1, 4, 2, 5, 0, 3, 7]
        while left < right and alist[right] < value:
            right -= 1
        alist[left] = alist[right]

        while left < right and alist[left] >= value:
            left += 1
        alist[right] = alist[left]
    alist[left] = value

    quick_sort(alist, start, left-1)
    quick_sort(alist, left+1, end)

    return alist