1 ) Give a list of products and their quantity
{p1,3,timestamp} , {p2,4,timestamp} , {p3,4,timestamp},{p1,4,timestamp} . Write a API to get the top K elements in last 1 hour .

2)Huffman Coding

3)System Design - Tiny url , more focus on concurrency and threading issues .

4)Collection of iterators , given a collection of iterator write hasNext and next method
Example : {{4,3,2,1},{12,13},{6,7,8,9,10,11} . Your output should be

4,12,6,3,13,7,2,8,1,9,10,11

Was able to sovle 2nd ,was able to implement next function on the 4th question . For 1st question provided inputs like use of priorityQ with comparator on timestamp but then was not able to solve entirely . If anyone has done first question ,plz do post