OpenAI Software Engineer interview experience

In the coding portion, I worked through a grid infection simulation: there was an n×m layout with initially infected plants, and infection spread to neighboring plants. The goal was to determine how many days it would take until there were no newly infected cells.

For the system design part, I was asked to design a payment system with a client, server, and bank. The flow started with a purchase request moving into an approved state, and then settlement didn’t have to happen in real time. Instead, transactions were batched: at midnight a file containing that day’s transactions was generated