Round 1:
https://leetcode.com/problems/walls-and-gates (premium)

Round2:
Suppose you have parents and children

1. come up with a data structre which represents their relactionship
2. Given a pair - find if they are related or not.

Extend the above sineario if you have grandchildren also

Round 3:
Given a stream of integers and target. find all the two pair of numbers which equals target.

Round 4:
Derive an data strcuture which does get(int key), put(int key, int val) and setAll(int val) in constact time-o(1)

setAll(int val) - overrides all the exciting key values to val.