How would you design a thread-safe hash map?

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Heaps & Maps Interview Questions

  1. [JUNIOR] What is a heap data structure and what are its main types?
  2. [JUNIOR] What is a hash map and how does it store key-value pairs?
  3. [MID] How do hash maps handle collisions using chaining versus open addressing?
  4. [MID] How do you find the Kth largest or smallest element in an array using a heap?
  5. [SENIOR] How do you design and implement an LRU cache using a hash map and doubly linked list?
  6. [JUNIOR] What is the difference between a min-heap and a max-heap?
  7. [JUNIOR] What is a hash function and why is it important for hash maps?
  8. [JUNIOR] What is a priority queue and how does it relate to a heap?
  9. [JUNIOR] What is a hash collision and how does it occur?
  10. [JUNIOR] What are the time complexities of basic hash map operations like insert, delete, and search?
  11. [MID] How does the heapify operation work and what is its time complexity?
  12. [MID] How do you build a heap from an unsorted array in O(n) time?
  13. [MID] How does heap sort work and what are its time and space complexities?
  14. [MID] What is the load factor in a hash map and how does it affect performance?
  15. [MID] How does a hash map handle resizing and rehashing?
  16. [MID] How would you use a hash map to solve the two-sum problem?
  17. [SENIOR] How do you merge K sorted lists or arrays using a heap?
  18. [SENIOR] How do you find the median from a data stream using two heaps?
  19. [SENIOR] How do you solve the top K frequent elements problem using a heap and a hash map?
  20. [JUNIOR] How is a binary heap represented using an array?
  21. [JUNIOR] What are the time complexities of basic heap operations like insert, extract, and peek?
  22. [JUNIOR] What is the difference between a hash map and a hash table?
  23. [MID] What is the difference between a heap and a binary search tree?
  24. [MID] What are the differences between a HashMap, TreeMap, and LinkedHashMap?
  25. [MID] How do you implement a min-heap or max-heap from scratch?
  26. [MID] How would you use a hash map to count word or character frequencies in a string?
  27. [SENIOR] How are heaps used in graph algorithms like Dijkstra's shortest path and Prim's minimum spanning tree?
  28. [SENIOR] How do you handle custom object keys in a hash map and what contract must be maintained between hash code and equality?
  29. [SENIOR] What is consistent hashing and how is it used in distributed systems?
  30. [JUNIOR] What are common real-world applications of heaps?
  31. [JUNIOR] What are common real-world applications of hash maps?
  32. [JUNIOR] What is the difference between a hash set and a hash map?
  33. [MID] Why are heaps preferred over balanced BSTs for implementing priority queues?
  34. [SENIOR] How would you implement a task scheduler using a priority queue?
  35. [SENIOR] What are the trade-offs between different collision resolution strategies in hash maps?
  36. [SENIOR] How would you design a thread-safe hash map?
  37. [MID] Are heaps always fully sorted and how does their ordering property differ from a sorted array?
  38. [SENIOR] How would you implement a priority queue that supports an efficient decrease-key operation?
  39. [SENIOR] How would you implement a hash map with O(1) time complexity for insert, delete, and getRandom operations?
  40. [EXPERT] What are Fibonacci heaps and how do they improve amortized time complexity for graph algorithms?
  41. [EXPERT] How do concurrent hash maps achieve thread safety through lock-free or fine-grained locking techniques?
  42. [EXPERT] What are binomial heaps and when would you use them over binary heaps?
  43. [EXPERT] How would you design a real-time event processing system using heaps for scheduling?
  44. [EXPERT] How would you implement a mergeable heap and which data structures support efficient merge operations?
  45. [EXPERT] How does Robin Hood hashing improve on standard open addressing?
  46. [EXPERT] What is cuckoo hashing and what guarantees does it provide for lookups?
  47. [EXPERT] What is perfect hashing and when can it be applied?
  48. [EXPERT] What are the cache performance implications of array-based heaps versus pointer-based tree implementations?