Hashing — DSA Technical Interview Questions & Answers

Hashing

Hashing

  • Hashing 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 Hashing.
  • From the example next to this theory: Hashing — 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 Hashing? Then show key % size + collision plan. Then name the trap.

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

Code Examples for Hashing

Hashing — working example

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

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

How to Explain Hashing to an Interviewer

What is Hashing?

Used for name → phone a diary Not just the heading

Give one small example of Hashing.

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

What mistake do beginners make with Hashing?

bad hash → pile-up Show the fix

Where do you use Hashing?

a diary name → phone