def algo(nums):  # nums: List[int]
    n = len(nums)
    if n <= 1:
        return nums

    nums1 = nums[:n // 2]
    nums2 = nums[n // 2:]

    result = []
    for num1 in nums1:
        for num2 in nums2:
            result.append(some_work(num1, num2))

    for num in nums:
        result.append(num)

    return result