sum_of_subset.py

def is_sum_subset(arr: list[int], required_sum: int) -> bool:
    """
    >>> is_sum_subset([2, 4, 6, 8], 5)
    False
    >>> is_sum_subset([2, 4, 6, 8], 14)
    True
    """
    # a subset value says 1 if that subset sum can be formed else 0
    # initially no subsets can be formed hence False/0
    arr_len = len(arr)
    subset = [[False] * (required_sum + 1) for _ in range(arr_len + 1)]

    # for each arr value, a sum of zero(0) can be formed by not taking any element
    # hence True/1
    for i in range(arr_len + 1):
        subset[i][0] = True

    # sum is not zero and set is empty then false
    for i in range(1, required_sum + 1):
        subset[0][i] = False

    for i in range(1, arr_len + 1):
        for j in range(1, required_sum + 1):
            current_item_value = arr[i - 1]

            # current_item_value is greater than j
            if current_item_value > j:
                subset[i][j] = subset[i - 1][j]
            # replace an 'if' in an 'else' to make the fluxe more clean
            else:
                without_current_item = subset[i - 1][j]

                sum_required_if_item_taken = j - current_item_value
                without_current_item = subset[i - 1][sum_required_if_item_taken]
                subset[i][j] = without_current_item or without_current_item

    return subset[arr_len][required_sum]


if __name__ == "__main__":
    import doctest

    doctest.testmod()