Interview OS
Back to AI Mock Interview

Mock Interview

Coding

Problem solving, communication while coding, and correctness.

Mock mode

Overview

The coding interview evaluates how you turn a problem into working, tested code under time pressure. Interviewers weigh clarifying questions, approach, complexity analysis, and communication as much as the final solution.

How it works

Mock mode
UnderstandApproachCodeVerifyExamplesI/OBrute→bestO(n)Clean impldry-runEdge cases
ClientServiceEdgeData

Step by step, with examples

  1. 1

    Examples

    • Restate the problem with test cases.
  2. 2

    Brute→best

    • State the naive plan, then optimize.
  3. 3

    Clean impl

    • Write readable, tested code.
  4. 4

    Edge cases

    • Trace through and give complexity.
    • Example: empty/dup inputs

What it tests

Problem solving, communication while coding, and correctness.

Format & timing

45–60 min · 1–2 problems on a shared editor · think aloud.

Sample questions

  • Solve a medium array/string problem while narrating your approach.
  • Given a stream of numbers, return the running median.
  • Find the shortest path in a grid with obstacles.

Model-answer walkthrough

  • Clarify inputs, outputs, and constraints; ask about edge cases.
  • State a brute-force approach and its complexity first.
  • Optimize, explaining the pattern you're applying.
  • Code cleanly while talking; then dry-run with an example.
  • Test empty / single / large / duplicate inputs.

What good looks like

  • Communicates before and while coding
  • Reaches an optimal-enough solution
  • Clean, correct code
  • Tests and handles edge cases

Likely follow-ups

  • What's the time/space complexity?
  • How would you handle the input not fitting in memory?
  • Can you make it cleaner?

Common mistakes

  • Silent coding
  • Jumping to code before clarifying
  • Skipping edge-case tests
  • Not stating complexity

Pre-round checklist

  • Warm up on 2 problems beforehand
  • Have a verbal template: clarify → brute → optimize → code → test
  • Practice on a plain editor (no autocomplete)

Where this content comes from

For full transparency, this content is curated and verified from these sources:

AI-generated, role & company-aware questionsReported interview formats by companyCalibrated against real interview rubrics