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🧮 Algorithms & data structures: iOS interview questions

1. What is Big-O notation and why is it needed? Junior PRO
2. Array vs linked list — what's the trade-off? Junior PRO
3. What is a hash table and how are collisions resolved? Middle PRO
4. Stack and queue — how do they differ and where are they used? Junior PRO
5. How does binary search work and what are its requirements? Middle PRO
6. Compare simple and efficient sorts. Middle PRO
7. What is recursion and why is it dangerous? Middle PRO
8. What is a tree and a binary search tree (BST)? Middle PRO
9. How would you check if an array has two numbers summing to X? Middle PRO
10. Fibonacci sequence Middle PRO
11. Array complexity Junior PRO
12. Set and Dictionary complexity. Advantage over Array? Junior PRO
13. How is a Dictionary (hash map) built? Senior PRO
14. What is ContiguousArray and why use it? Senior PRO
15. How does NSArray differ from Swift Array? Middle PRO