0130 min suggested
Reason about string windows
Find the longest substring without repeating characters. Walk through a repeated character, an empty input, and a string with all unique characters.
What a strong answer demonstrates
Correct window updates, explicit character assumptions, and linear-time reasoning.
0240 min suggested
System design
Design a notification service. Clarify delivery guarantees, model the data, then handle retries and duplicate events.
What a strong answer demonstrates
Clear requirements, a working baseline, and explicit trade-offs.
0320 min suggested
Behavioral storytelling
Describe a technical decision you changed after receiving feedback. Explain your contribution and the outcome.
What a strong answer demonstrates
Specific actions, honest reflection, and measurable impact.