It's not about the optimal solution
The biggest misconception candidates have is that getting to O(n) wins the interview. What actually matters: does the candidate communicate clearly, catch their own bugs, and demonstrate how they'd handle edge cases in production?
The four things interviewers score
Based on our analysis of interview sessions: 1) Problem decomposition — can you break a big problem into smaller pieces? 2) Correctness — does the code produce the right output? 3) Efficiency — do you know why your solution has the complexity it does? 4) Communication — does your thinking make the interviewer's job easier?
The optimal 45-minute structure
Minutes 1–5: Clarify requirements, state assumptions, confirm examples. Minutes 5–15: Talk through approach before writing a single line of code. Minutes 15–35: Code while narrating. Minutes 35–40: Test with the given examples, then edge cases (empty, single element, duplicates). Minutes 40–45: Discuss complexity, improvements, follow-ups.
// Always start by restating the problem // "So I need to find two indices whose values sum to target. // I'll assume exactly one solution exists. Can I return in any order?" // Approach: hash map to track seen values // Time: O(n), Space: O(n)
What gets you hired at Staff+ level
At Staff level, interviewers want to see that you naturally consider distributed systems implications, failure modes, and how your solution scales. Even for a LeetCode problem, mention: 'In a production context, this hash map would be a cache — I'd think about eviction and consistency.'