I was sent an OA that I was given 72 hours to complete. I spent around 13 hours on it. It was essentially asking to code an orderbook.

I passed 29 of the 30 test cases within 3 hours and spent another 10 on the last test case.

After rigorously profiling my code, I realized that the bottleneck for the last test case (number 29's) was reading from std::cin. Akuna expected way too much input to be read from std::cin within the 2-second time interval.

The test case essentially submitted a bunch of orders that never matched, so it was impossible for my order processing code to be the bottleneck.

It's a shame that Akuna doesn't realize that HackerRank is leading to their candidates failing the 29th test case, mistaking candidates as not meeting their 'technical bar'.

Don't waste your time here. Read the reviews on Glassdoor and move on to another firm if you're interested in finance.

Code an orderbook with GTC and FillAndKill order types.