How to add padding in a dataset to fill up to 50 items in a list and replace NaN with 0?

Question

I have the following encoded text column in my dataset:

[182, 4]
[14, 2, 31, 42, 72]
[362, 685, 2, 399, 21, 16, 684, 682, 35, 7, 12]

Somehow