Think fast


  1. Water lilies
    Water lilies growing in a lake and every day their quantity doubles - 1, 2, 4, 8, 16, and so on. It takes 48 days for them to completely cover the entire lake.
    • Q: How long will it take for lilies to cover half of the lake?
  2. Remote code (for developers)
    You are working remotely from Russia (Ural) for Los Angeles financial startup. There is a production server there, many people working on it concurrently. The main rule: there can't be any downtime for server (even if in a second thousands of users do selects, inserts and etc.). You need to modify a column type in 4M rows database there and also make changes in code that works with this column.

    • Problem: there is a latency between you and server, also if you modify code and DB migration is not ready — downtime occurs. If migration ready, but code is not uploaded yet — downtime occurs. You have no time to use replication or similar time-consuming activities (have only 2 hours to solve).
      What would be your approach and solution for this case?

  3. Bat and ball
    The bat and ball cost $ 1.10 in total. How much does the ball cost if the bat is $ 1 more expensive?
  4. Numbers 
    Five machines make five products in five minutes. How long does it take 100 machines to make 100 pieces?
  5. Numbers 
    What is pow(256; 0,25)