1. Design a cron parser.
2. Design a system where a user can claim a reward only once, allowing for over-distribution but not under-distribution.
3. Describe how you would design a system to distribute 6 million burgers to customers in a highly concurrent environment.
4. Design a system to handle a flash sale of 10 million burgers for 10 minutes.
5. Design a system to give away 6 million burgers in 10 minutes.