Delhivery | SDE 1

Round 1 Introduction and short discussion on my current work and product. DS / ALGO 1. Top View of a Binary Tree (Code) 2. Check if given Tree is BST or...

Round 1 Introduction and short discussion on my current work and product.
DS / ALGO
1. Top View of a Binary Tree (Code)
2. Check if given Tree is BST or not (Code) - multiple approaches
3. Discussion on BST like data structure with duplicates
4. How HashMap internally works - explain worst case scenario in case of collisions
5. Discussion on BBSTs
* Need to explain the time and space complexties for all the solutions. Also time complexities of different operations in any DS which are being used in code.

OOPs / Java
1. Overloading vs Overriding
2. What if 2 functions in a class have same name and input paramaters but different return types. Will it work?
3. Runtime Polymorphism usecases with code
4. Inheritance related questions with code
5. Throw vs Throws
6. Finally block usage. Can it be used without try and catch. Can we put some code after try / catch but before finally block?
7. Generics in Java and it\'s advantage

Spring
1. What is the use of @SpringBootApplication annotation
2. Tell about @ComponentScan annotation in detail
3. How to configure multiple profiles (Dev, Test and Prod) in Spring Boot application
4. Discussion on application.properties file
5. What is @Bean annotation and what annotation we need to give at class level if we use it for any method
6. What is Spring Security and where did I use (no Syntax, just basic overview)

Kafka
1. What is Kafka
2. Advantages of using Kafka
3. How many consumers can read from a topic
4. Can a topic be written by multiple producers

Round 2 (Interviewer was the Team Lead of Platform team)

Detailed discussion on the work I do at my current org and discussion on the product I am working in.
Interviewer was more interested to know the impact I have made there.

1. What DBs have you used. Explain the challenges faced with those DBs.
2. Discussion on SQL blockages and ISOLATION levels
3. SQL --> Given a person_details table with columns as id, name, gender, dob:
   a) Retrun all the person ids for all females having dob between 2000 to 2020
   b) How would you go about stroing additional information for address
   c) How would you make sure ZERO downtime on DB while introducing address details in db
   d) How would you store education details for a person
   e) Discussion on ways to optimize SQL queries. Advantages / Disadvantages of indexing
4. How would you introduce Search functionality using SQL DBs. Can I use any other DB to achieve this ?
5. How Elasticsearch works internally
6. What things do I check while doing Code reivew
7. What do you mean by RESTful web services
8. What do you mean by Resources in REST
9. Write REST endpoints for shopping cart functionlity (add/delete/update product or product quantities)
10. Design an E-commerce shopping cart (LLD)
11. How to make sure guest user doesn\'t lose cart items if he reloads the page
12. Discussion on caching and in-memory dbs (Redis)
13. How would you store Order transaction details
14. How would you store Product details in db. Why did you choose NoSQL (Document based) db for this purpose.
15. Generally, how would you take call which DB to use

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