Optimizing Existing Algorithms for Performance

Context

At companies like Stripe or Netflix, interviewers often ask how you would improve a working but slow algorithm. They want to see structured reasoning, not just a faster final answer.

Core Question

Explain how you would optimize an existing algorithm to improve performance. In your answer, address:

1. How you identify the current bottleneck in time or space.
2. What optimization techniques you would consider, such as better data structures, preprocessing, caching, or algorithmic redesign.
3. How you validate that the optimized version is actually better and still correct.

Scope Guidance

Focus on a practical engineering approach: start from baseline complexity, profile or reason about hot spots, propose targeted improvements, and discuss trade-offs. You do not need to cover low-level compiler or hardware tuning unless it directly affects the algorithmic design.