[ OK ]5f36f1d7-aa4f-4398-b488-15f494cdc06e — full writeup
[ INFO ]category: Behavioral · Multiple Types difficulty: 6 freq: first seen: 2026-03-03
[6][MULTIPLE TYPES]Social NetworkSystem Design
$catproblem.md
OpenAI — Software Engineer ❌ Failed
Level: Mid-Level
Round: Full Journey · Type: Multiple Types · Difficulty: 6/10 · Duration: 120 min · Interviewer: Friendly
Topics: Social Network, System Design
Location: San Francisco Bay Area
Interview date: 2026-01-21
Got offer: False
Summary
Round 1: Coding
Question: Implement a social network API with follow, unfollow, snap, and is_following functionalities. I was given a prompt about a 2-player game. I was unable to complete the implementation with correct logic.
Round 2: System Design
Question: Design a payment system to handle hold payments, batch processing, and charge payments. I also asked the interviewer about OpenAI.
Details
Preparation Tips & Key Takeaways
What I Learned
I need to be prepared for LeetCode-style coding questions, even when expecting a different type of problem.
System design questions require a solid understanding of fundamental concepts.
Recommended Preparation
Coding Practice
Practice implementing social network-related APIs.
Focus on writing clean and bug-free code under pressure.
System Design
Study payment system designs, including handling different payment states and batch processing.
Review common system design patterns and tradeoffs.
Resources I Recommend
LeetCode for coding practice.
System design resources like blogs and books to understand different architectures.
Common Pitfalls to Avoid
Not being prepared for standard coding questions can be a major pitfall.
Insufficient knowledge of system design principles can lead to incomplete or flawed designs.