I made a video editorial discussing D. Birthday Gift from last Div 2 Round (CF Round 936). The video talks about how the concept of submasks can be helpful outside of subset counting problems.

Youtube Link : https://youtu.be/qZobx4EOVm0?si=LsPPCv4mi2szw-PR

Here's a practice contest on bitwise operations:

• Practice Contest 1

If you need any help or hints for the practice problem, you can ask on my Discord Server or on the Twitter thread. In case you are interested, you can also checkout my youtube channel