# Interview Pattern Extra 142

## Problem shape
Interviewers use **Interview Pattern Extra 142** to test whether you can state invariants, pick the right data structure, and talk through edge cases without freezing.

## Approach
1. Restate constraints and examples.
2. Start with a brute force so the interviewer knows you understand correctness.
3. Tighten to the target complexity; name the bottleneck.
4. Walk one dry-run on the board, then discuss follow-ups.

## Talking points
- Clarify input sizes and whether online or offline queries are allowed.
- Name the invariant you maintain after each step.
- Call out off-by-one and empty-input cases before coding.
- Mention a verification idea (small brute force, property test).

## Practice tip
Rehearse the explanation out loud once before you type. Tools like [AI help for online coding assessments](https://www.linkjob.ai/interview-copilot/) can help you keep a calm structure when the round is live.

## Complexity
State time and space clearly, then ask whether the interviewer wants a follow-up (online version, parallel, or memory-tight).