Got this question in my phone screen today. It's a three part question,

Given a shipping yard with infinite capacity for containers and has clients who would like to store their containers. Design a system which can manage the operations of the yard.

1. start with a client intending to add or remove containers, i.e. (containers, amount)
2. improve functionality by extending the system to buying and selling operations, maintain a order book where logs of each buy and sell order requests are logged
3. introduce bidding for each buy and sell request, based on the best offer, make the transaction.

Was asked to explain complexity of the solution as well as where I could have improved.