How do you find the maximum XOR of two numbers in an array?
PICTURE THIS: ARRAY IN MEMORY
Index starts at 0. Scan once for max — O(n).
Simple meaning
Build a binary trie of bit prefixes (or grow a prefix-xor set bit by bit from the high bit) and for each number greedily try the opposite 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:
- 1Build a binary trie
of bit prefixes (or grow a prefix-xor set bit by bit from the high bit) and for each number greedily try the opposite bit.
- 2Time is O(n *
32) and space is O(n * 32).
- 3Checking all pairs is
O(n^2) and too slow.
- 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
Build a binary trie of bit prefixes (or grow a prefix-xor set bit by bit from the high bit) and for each number greedily try the opposite bit. Time is O(n * 32) and space is O(n * 32).