[Zero Two]

Coding interviews get a lot of justified criticism but for most engineering roles they're still the gate you have to get through. Here's what actually works based on personal experience and talking to people who do a lot of hiring.

What interviewers are actually evaluating
Most good interviewers aren't primarily evaluating whether you've memorised the optimal solution to a specific problem. They're evaluating: can you communicate your thinking, do you handle edge cases, can you take a hint and adapt, are you pleasant to work with under mild pressure.

The preparation that matters

• LeetCode: medium questions, topic by topic. Arrays, strings, hashmaps, two pointers, sliding window, binary search, BFS/DFS, dynamic programming. You don't need to do 500 questions - you need to understand the patterns.
  
• Implement data structures from scratch. Linked list, stack, queue, binary tree, hash table. Once. You'll rarely be asked to implement them but understanding them makes everything else easier.
  
• Practise talking while coding. Narrate your approach before writing. Most interview failures are communication failures, not algorithmic ones.
  
• Mock interviews. Pramp, interviewing.io, or a friend with a whiteboard. The format is a skill and needs practice separately from the problem-solving.
  

System design (for senior roles)
Read "Designing Data-Intensive Applications" (Kleppmann). Understand: load balancing, caching (Redis), databases (SQL vs NoSQL, indexing, replication), message queues, CDNs, rate limiting. Practice designing Twitter/Uber/URL shortener.

What to do in the interview
1. Restate the problem and confirm constraints before touching code
2. Talk through your approach first, get early feedback
3. Code clean and readable - names matter more than brevity
4. Test with the obvious case, then edge cases
5. Know the time/space complexity of your solution

The honest truth: the prep is boring and takes 2-3 months of consistent effort. There's no shortcut but it's a learnable skill.