Heady Interview Experience for Backend Engineer

I applied for a Backend Engineer profile at “Heady“, the platform through which I applied was “WellFound“. “Heady” is a mobile product consultancy, that builds sustainable innovation through bits and pixels.

The job description read as:

• Experience with two or more development languages preferably TypeScript for Node.js, Java, C#, Python, etc.
• Proficient in writing REST APIs, Have a good understanding and knowledge of API Standards, and follow the best practices.
• Experience with one or more databases preferably NoSQL (MongoDB), SQL, etc.
• Write high-quality, well-tested code and be comfortable with Object-Oriented programming and Design Principles.
• Comfortability with Agile methods, such as Extreme Programming (XP), Scrum and/or Kanban, TDD
• Bonus points if you have a working knowledge of cloud technology such as AWS, Docker, and Kubernetes.

About Me:

I am a 2021 graduate in Information Technology, did an internship in Android in Ed Tech StartUp, and then started as a Digital Specialist Engineer in Infosys Ltd. on 16 August 2021. Left Infosys Ltd. on 12 May 2023. Thus having 1 Year and 9 Months of experience.

The job application was done on 25 July 2023, and I got a revert on 02 August 2023 that my profile is accepted. Then got a mail on 03 August 2023 asking for details such as Current CTC, Expected CTC, and Notice Period I replied and my Interview got scheduled on 10 August 2023.

Questions asked in the Interview:

• Difference between String and String Builder.
• Difference between Collection and Collections.
• The Algorithmic Problem was:

You are given a string containing characters A and B only. Your task is to change it into a string such that there are no matching adjacent characters. To do this, you can delete 0 or more characters in the string. Your task is to find out the minimum number of required deletions.

Example s = "AABAAB"
Remove an A at positions 0 and 3 to make ABAB in two deletions.
Input: "AAAA"
"BBBBB"
"ABABABAB"
"BABABA"
"AAABBB"
Output:
3
4
0
0
4

• What is the load factor in HashMap, what will happen if we increase it?
• How HashMap gets an element in O(1)?
• Difference between List and HashSet, how HashSet deals with duplicate elements?
• How to prevent DDOS attacks in Spring Boot?
• SQL is horizontally scalable or vertically scalable?

Result: Expecting a rejection mail as I was only able to do the given algorithmic problem and didn’t answer theory concepts well.