How do you find the First Non-Repeating Character in a Stream?
This question asks for an efficient algorithm to track unique characters in real-time. It tests hash map and queue usage.
Why Interviewers Ask This
Streaming data processing is common in analytics. Interviewers ask this to evaluate your ability to maintain state efficiently. It demonstrates proficiency with data structures for dynamic inputs.
How to Answer This Question
Use a frequency map and a queue. Add new chars to queue and update map. Remove front of queue if count > 1. Return front of queue as answer.
Key Points to Cover
- Frequency map
- Queue for order
- Efficient removal
- Real-time updates
Sample Answer
To find the first non-repeating character in a stream, maintain a frequency map and a queue. As characters arrive, update their counts. If a character's count exceeds one, remove it from the queue until a valid candidate…
Common Mistakes to Avoid
- Re-scanning the string
- Not removing duplicates from queue
- Ignoring stream nature
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