Sum of elements (can be repeated) of subarrays equal to a target value in Python

Question

def howSum(targetSum, numbers):
    if targetSum == 0:
        return []
    if targetSum < 0:
        return None
    for num in numbers:
        remainder = targetSum - num
        remainderResult = howSum(remainder, numbers)
        if remainderResult != None:
            return [remainderResult, num]
    return None

I have tried this code and getting the answer [[[[[], 2], 2], 2], 2] instead of [2, 2, 2, 2]. I am quite new to programming and stack exchange. Please help me out here. Thanks in advance

Answer 1

Use sequence unpacking.

Instead of:

            return [remainderResult, num]

Use:

            return [*remainderResult, num]

Full code:

def howSum(targetSum, numbers):
    if targetSum == 0:
        return []
    if targetSum < 0:
        return None
    for num in numbers:
        remainder = targetSum - num
        remainderResult = howSum(remainder, numbers)
        if remainderResult != None:
            return [*remainderResult, num]
    return None'

Output:

[2, 2, 2, 2]