Hash Table — DSA Technical Interview Questions & Answers

Hash Table

Hash Table

  • Hash Table is a DSA topic. In plain words you use it for name → phone in a diary. Don’t start with a slogan — start with that picture.
  • Smallest example: key % size + collision plan. Type it, run it, and say what you see. If you can do that from memory, you know Hash Table.
  • From the example next to this theory: Hash Table — hash maps give average O(1) insert/lookup — dict in Python.
  • Trap: bad hash → pile-up. Fix that before you talk about advanced DSA.
  • Viva: what is Hash Table? Then show key % size + collision plan. Then name the trap.

Technical Interview Tip: What is Hash Table? Show this: key % size + collision plan. Trap: bad hash → pile-up.

Code Examples for Hash Table

Hash Table — working example

freq = {}
for ch in "banana":
    freq[ch] = freq.get(ch, 0) + 1
print(freq)
print(freq.get("a"), freq.get("z", 0))

Hash Table — hash maps give average O(1) insert/lookup — dict in Python.

How to Explain Hash Table to an Interviewer

What is Hash Table?

Used for name → phone a diary Not just the heading

Give one small example of Hash Table.

key % size + collision plan Hash Table — hash maps give average O(1) insert/lookup — dict in Python

What mistake do beginners make with Hash Table?

bad hash → pile-up Show the fix

Where do you use Hash Table?

a diary name → phone