How do you reverse the bits of a 32-bit unsigned integer?
PICTURE THIS: OOP PILLARS
Simple meaning
Swap bits with masks in log steps (1,2,4,8,16) or loop 32 times shifting result left and feeding n's low bit.
WHY — Bit Manipulation instead of guessing?
Why interviewers care about Bit Manipulation:
question about Bit Manipulation.
trade-offs, and what you would actually do on a DSA project - not buzzwords.
Name the idea, why it exists, then one short example.
End with when you use it and one common pitfall.
STEPS — What happens step by step?
Before you speak the answer, walk the interviewer through these steps:
- 1Swap bits with masks
in log steps (1,2,4,8,16) or loop 32 times shifting result left and feeding n's low bit.
- 2Time is O(1) word
operations or O(32), space O(1).
- 3A 8-bit lookup table
is the systems-style follow-up.
- 4Give an example
One tiny concrete case you can say aloud.
- 5Common mistake
What juniors usually get wrong.
- 6Close
When you pick this over the alternative.
EXAMPLE — See it in action
Here's a short line you can speak, broken into clear beats:
Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.
Key takeaway
Swap bits with masks in log steps (1,2,4,8,16) or loop 32 times shifting result left and feeding n's low bit. Time is O(1) word operations or O(32), space O(1).