Module 3 · Recursion, trees and the questions you cannot prepare for Lesson 10 of 15
When you go blank
The recovery routine: restate the question, name the pattern family, start with the brute force, then improve it. Most candidates who are rejected went silent instead of doing this.
The concept
Going blank happens to everyone, including people who have solved three hundred problems, because the interview is a different task from practising. The recovery is a procedure, not a mood: restate the question in your own words, work the smallest example by hand, then describe the brute-force solution out loud.
Naming the brute force is not giving up; it is a floor to stand on. Say "the straightforward way is O(n²) — let me write the skeleton and then improve it", and you are talking, the interviewer can steer you, and partial credit is on the table. Many candidates then spot the improvement while writing the slow version.
Recovery procedure:
1. Restate the question in your own words.
2. Work the SMALLEST example by hand.
3. Say the brute force out loud: "the simple way is O(n^2)...".
4. Ask about the input: size? duplicates? empty?
Naming the brute force is a floor to stand on, not giving up.Common mistakes
The mistake is going quiet and waiting for inspiration, or worse, starting to write code you cannot explain. Ask a clarifying question about the input instead — size, duplicates, empty cases — the answer usually hands you the pattern.
Worked example
"I do not have the optimal answer yet. A brute-force version is O(n²) and would work; may I describe that and then improve it?" is a strong answer, not a confession.
Your practice task
Practise two problems you cannot solve: spend ten minutes narrating the brute force and the path you would explore, and never say only "I do not know".
Do this before moving on. Reading a solution teaches the shape of it; typing it teaches you.
Key takeaway
Going blank happens to everyone, including people who have solved three hundred problems, because the interview is a different task from practising.
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