高频题（0）
1. Design APIs for a TextDocument Class
Design a TextDocument class that implements several APIs: apply_operation, undo_last, redo_last, get_current_content. The apply_operation should support two main operations: appending a string and deleting a string. Discuss how you would implement these features.
2. Improve Notion's Task Queue System
Propose improvements for the existing Notion task queue system to support sub-tasks. Discuss how you would design subtasks and the overall architecture.
3. Past Project Deep Dive
Discuss two of your top projects in detail. Present them freely and talk about possible improvements if you were to do them again.
4. Design a Calendar System
Design a calendar system. Discuss the data structures you would use, how you would handle events, reminders, and user interaction.
5. Write a Nested TODO List
Write a TODO list application that supports the creation of nested TODO lists, where each list can contain sub-tasks.
