Optiver SWE Intern in Sydney: a brutal OA, a fast-paced behavioural round, TCP/UDP fundamentals and an order book LLD at the Superday

I applied online for the SWE Intern position at Optiver, Sydney. The entire process took about 2 months. The initial test was a difficult OA, speed was important and it featured an LLD task requiring a custom data structure that combined a min/max heap with lazy deletion, a hashmap, and a Fibonacci sequencing component all in a single problem. I'd study the LLD questions here to be ready for it.

After the OA, the process moved into an initial behavioral interview followed by a technical screen. The behavioral round was surprisingly fast-paced and stressful compared to typical culture-fit conversations. Technical screen was more straightforward, mostly focused on core CS fundamentals. One question they asked was the differences between TCP/UDP.

Final stage was a virtual Superday, three rounds, 2 technical and one more behavioral. One of the technical rounds was Zap N. The other was LLD and asked about building a trading engine component. The core problem required implementing an order book data structure with three primary functions: inserting a new order, deleting an existing order, and retrieving the total volume at a given price level. The behavioral questions again were like "Why did I want to work at Optiver", and "tell me about a situation where I dealt with criticism, conflict".