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Congratulations. You have mastered the internals of computer science. In this final module, we summarize the 3 types of questions you will face at FAANG level interviews.
Question: "You have a list of 1 billion IDs. How do you find the unique IDs in under 500MB of RAM?"
Architect Answer: "I wouldn't use a HashSet (too much RAM). I would use a Bloom Filter (probabilistic) or a Bitset (bit-map) if the IDs are numeric. This allows me to trade a tiny bit of accuracy for a 99% reduction in memory footprint."
Question: "Why would you choose a slower algorithm on purpose?"
Architect Answer: "Reliability and Maintainability. For example, replacing a complex Recursive DP with a simple iterative loop might lose 5% speed but prevents **Stack Overflow crashes** and makes the code 10x easier for the dev team to debug at 3 AM. A senior architect optimizes for the **System**, not just the algorithm."
You are now equipped with the tools to solve any engineering problem. Use them wisely. Build something great.
Quizzes linked to this course—pass to earn certificates.
On this page
1. The "Scale Up" Question 2. The Algorithmic Trade-off