The process was smooth. The HR team was really helpful. They assigned a room to each candidate, and interviewers came to them. They offered free lunch to every candidate.

Round 1:

1. Brief discussion about previous projects.

2. Reason for using particular technologies in the project (e.g., why MongoDB was used).

3. Find unique pairs of sums in an unsorted array. Example: array a[] = [4, 3, 1, 2, 5] Print pairs whose sum is 5. Answer: (1, 4), (2, 3)

4. In a Linked List, delete a node without having a reference to the head node. You are given a reference to the node to be deleted, and the order of the linked list must remain the same. Example: Linked list 1 -> 2 -> 3 -> 4 -> 5 -> null The reference is at node 3, not the first element. Delete node 3 from the list.

5. What is a Singleton Class in Java? How to create one?

6. Internal working of a HashMap.

Round 2:

1. Detailed discussion about the project.
2. If a server is capable of handling 10 requests at a time, and 100 hits come simultaneously, how to handle this situation?
3. Binary Tree Data Structure Questions: Find the height of a tree.
4. Level Order Traversal of a Binary Tree.
5. What improvements did you bring to your project?
6. Name some key challenges that you fixed.

Round 3:

1. Brief discussion on the project.
2. Design a Messenger System.
3. Stateful vs. Stateless.
4. What is Caching?
5. How does Redis store data? Why did you use it in your project?
6. REST vs. SOAP.
7. Why Walmart?