The interview consisted of three technical parts, each lasting 40 minutes, with a 20-minute break in between.

Each part was different:

• The first was about software design.
• The second was a classic medium-level LeetCode question, which I needed to implement in a language I was not familiar with (in my case, Go).
• The last part was about reviewing code and answering some questions about it.

Design a class for a regular deck of cards that supports the following operations:

• Shuffle
• Draw (from the top)
• Sort

Happy number question (well-known question; google it) and implementation in an unfamiliar language.