Freecharge Interview Experience-Lead SDE

Round1:

1) Design, develop and implement an elevator problem (only 20 minutes) Lots of discussion on why the approach is chosen. Advantages and trade-offs discussed.(For almost an hour)

Round2:
1) All possible permutations of a string.
2) Design, develop and implement Phone directory. Implement a search algorithm on top of it ..so that it does autocomplete Eg : %95% ( Result : 98769512345, 9545654312 etc having 95 sequence anywhere)
(Note : Not to use TRIE)
3) Design, develop and implement an OrderGenerating System in distributed servers.

Conditions:
1) No database should be used.
2) The orderID generated should be unique among all servers.
Lots of discussion on various approaches.
4) Difference between equals and hashcode in JAVA



Round3:(Hiring Manager Round)
1) Details about projects in CV.Explanation in detail
2) Check if Binary Tree is BST or not?