1 coding round:

1. https://leetcode.com/problems/meeting-rooms-ii/
2. You are given n sticks with differing lengths. You need to get k sticks of the same length and return the maximum length. For example:
   sticks = [4, 7, 9]
   k = 4
   4 = (4)
   7 = (4) + 3
   9 = (4) + (4) + 1
   Answer: 4

2 coding round:

1. https://leetcode.com/problems/add-binary/
2. classic least common ancestor problem analogical to this problem https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree/, but node have parent link instead of left, right.

System design:
Write key-value storage
Some users can put values into storage. If you put some values to some key they collected to the array.
Another user can subscribe to some keys.
After the first key put, the timer start work, and after 100 seconds key evicted from storage, and subscriber get an array of put values.