Counting Bits - 28th May

Question Given a non negative integer number num. For every numbers i in the range 0 ≤ i ≤ num calculate the number of 1's in their binary representation and return them as an array.
Solution – 
def countBits(self, num: int) -> List[int]:
        
    res = [0]
    while len(res) <= num:
        res += [i+1 for i in res]
    return res[:num+1]