Courses › Coding Interviews › Getting Started

Introduction

How coding rounds are run and scored, and the 4 things interviewers watch for.

Coding interviews are the most standardized part of the software engineering loop: you're given a problem, a shared editor and 30–45 minutes, and asked to produce a working, efficient solution while explaining your thinking. They're also the most learnable — the same ~15 patterns underlie the vast majority of questions.

What interviewers evaluate

Getting the optimal answer silently, then failing to explain it, often scores *worse* than reaching a good solution while communicating clearly.

The shape of a 45-minute round

  • Clarify (3–5 min) — restate the problem, ask about input sizes, edge cases and expected output. Work through a small example.
  • Approach (5–10 min) — describe a brute-force solution and its complexity, then improve it. Agree on the approach *before* coding.
  • Code (15–20 min) — write the solution, narrating as you go.
  • Test (5 min) — trace through an example by hand, then edge cases: empty input, one element, duplicates, negative numbers.
  • Follow-ups — the interviewer may change constraints ("what if the input doesn't fit in memory?").

[!INTERVIEW] Brute force first, out loud Stating the brute-force solution proves you understand the problem and gives you a baseline to improve on. "The naive approach checks every pair, O(n²). We can do better by remembering what we've seen in a hash map, which brings it to O(n)."

Formats you'll encounter

  • Classic algorithmic — LeetCode-style problems on arrays, strings, trees, graphs and DP. Most big tech companies.
  • Practical / multi-part — build something realistic in stages (an in-memory database, a rate limiter, a file system), each level adding requirements. Increasingly common at AI labs and fintech.
  • Debugging / code reading — find bugs in an unfamiliar codebase.
  • AI-assisted — solve a problem with an AI assistant available. See AI-Assisted Coding.
  • Online assessments — timed, auto-graded tests taken alone, often the first step. See Online Assessments.

How this track is organized

  • How to Prepare — a pattern-first study plan
  • Big-O Cheat Sheet — complexities and how constraints hint at the solution
  • Python for Interviews — the standard-library toolkit and the traps to avoid
  • Patterns — each page explains when to recognize the pattern, a reusable template, and the common variations

Pick a language you're fluent in — Python is the most popular choice because its syntax is compact and its standard library (collections, heapq, bisect) covers most interview needs. See Python for Interviews.