Answer core Python, CS, DB, and testing questions

Fundamentals (Python / CS / DB / OS / Web / Testing)

Answer the following interview prompts. Keep answers precise, with examples and tradeoffs.

A) Testing & QA

1. In a project that includes data connection management , user management , and permission management , what are the main testing risk areas for each module?
2. Scenario: WeChat scan-to-pay (QR code payment). How would you design test cases ?

B) Python fundamentals

3. What are the three most basic characteristics of object-oriented programming ?
4. What are shallow copy and deep copy ?
5. Differences between list and tuple ?
6. Key characteristics of a dict ?
7. What is a decorator and why use it?
8. Difference between __init__ and __new__ ?
9. What is a generator ?
10. What is an iterator used for?
11. What is self ?
12. What is serialization/deserialization ?
13. Can Python have memory leaks ? How to avoid them?

C) Data structures & algorithms (conceptual)

14. What is a linked list ?
15. What sorting algorithms do you know? Which is “fast”?
16. Why is quicksort’s average time complexity $O(n\log n)$ ?
17. What are the characteristics of stack and queue ? When to use each?
18. What is a binary tree ? What traversal orders exist?
19. What is a red-black tree ?

D) Database & web/OS

20. What is a database index ?
21. Why can indexes speed up queries?
22. What is a B+ tree (why used for indexes)?
23. What is ACID in transactions?
24. What types of JOIN exist?
25. When a phone opens a webpage and content loads, what key technical steps happen?
26. Concepts of process vs thread ; key differences?