What technical interviews test
Interviewers are usually testing your reasoning, not just your recall. They want to see how you break down a problem, how you handle being stuck, and whether you can be coached in real time.
Think aloud, deliberately
Silent thinking is invisible thinking. Say what you're checking, what assumptions you're making, and why you're choosing an approach — even if it's just to rule it out.
"Silent for 90 seconds, then blurts an answer with no working."
"'Let me start by clarifying: is the array sorted? OK, assumed sorted. Two approaches — brute force O(n²) or two pointers O(n). I'll take two pointers because n could be large…'"
Why this works — The interviewer can now help you if you drift. Silence gives them nothing to work with.
When you don't know
The worst answer is a confident wrong one. The best is: 'I don't remember exactly — here's how I'd derive it / look it up / test it.' You're being watched for judgement, not omniscience.
I'd rather hire the candidate who says 'I don't know, let me reason from first principles' than the one who bluffs.
The three flavours
- Coding — LeetCode-style problems. Practise pattern recognition, not memorisation.
- Case — consulting-style structured problems. Frameworks help but don't force fit.
- Quant — probability, mental maths, brainteasers. Trading firms love these.