Doordash VO 面经

1月中旬的doordash VO， 一共4轮， senior职位：1. HM聊天，问了一些BQ，看看亚麻的BQ问题，这一轮应该不难。
2. Design a reward system based on the comment users provide. (if you have a comment for an item of a resturant liked by many ppl, you will get some rewards)
3. number of island, followup, what if it's not a m x n matrix.
4. 地里高频题，a. check "p1d1" valid or not.  b. given n, count & print valid pick up & delivery time strings. c. 求b里面f(n)的通项公式。

请教楼主这个Design a reward system based on the comment users provide 怎么准备 有啥资料吗 谢谢