Hash Tables Interview Questions | Data-Structures | NextRound

1What is the difference between HashMap, TreeMap, and LinkedHashMap?Intermediate

2How do you design a Hash Table from scratch?Advanced

3What is the significance of Equals() and GetHashCode() in C#/Java when using objects as keys?Intermediate

4What is the Load Factor? How does it trigger a Rehash/Resize?Intermediate

5Why is the worst-case lookup O(n)? How do modern implementations avoid this? (Tree buckets)Intermediate

6Why can't we use a Hash Table efficiently for Ordered operations (e.g., find min/max)?Intermediate

7Why is it bad to use a mutable object as a key in a HashMap?Intermediate

8What is Consistent Hashing? How is it used in Distributed Systems?Intermediate

9What is a Cryptographic Hash? How does it differ from a regular hash?Intermediate

10What is the average and worst-case time complexity for lookup in a Hash Table?Intermediate

11Explain Open Addressing. (Linear Probing, Quadratic Probing, Double Hashing)Intermediate

12Explain Separate Chaining. (Buckets/Linked Lists)Intermediate

13What is a Hash Collision?Intermediate

14What is a Bloom Filter? When is it used? (Cache penetration, Spell check)Intermediate

15What is a Hash Function? What makes a good hash function?Intermediate

16What is a Hash Table? What is a Key-Value pair?Beginner

17What are the security implications of Hash Collision attacks (HashDoS)?Advanced