Current Experience: 3 year+ at a product based MNC

Recently I appeared for Java Backend SDE 2 role in M2P.
There were total of 5 rounds mostly were 1 hour round.

Screening round:
It was taken by Intervue.io. It started with introduction from both side then he asked springboot and core java questions.
Asked few easy programming questions but needed to code using stream only.
It was good brain storming session around some java code puzzles.

Problem solving round:
It started with introduction from both side. Then asked to code following:

• Singleton design pattern
• Return list of all subString with only vowels. I gave O(n^3) solution then O(n^2) solution and want to give O(n) sliding window solution but he did not asked for further optimisation :( .

In the end he asked question around api endpoint security.

Coding evolution round:
It started with introduction. Then he jumped on some springboot and core Java questions.
Few simple code related to Java stream
He asked one coding question:
https://leetcode.com/problems/merge-sorted-array/description/

Design round:
It started with introduction and he straight came to design problem. He asked to design one system related to credit card with two requirement. First requirement was to notify the user at start of expiry month that card is gonna expire at end of month and second requirement was to expire the card itself and send notification to user that card got expired.
I clarified is it HLD or LLD. He said let’s start with HLD.
I started with listing these two functional requirements. Then I draw quite simple architectural diagram with couple of services. He cross-question in between about performance and I was able to tune it with discussions. In the end I was able to come up with good design interviewer was satisfied with.
Interview was quite helpful in this round giving hints in between. Frankly speaking, this was my first ever HLD round.

Culture Fitment Round:
This was 30 minute round. Interviewer was having overall 15 years of experience. It started with introduction from both sides.
He asked common question like:

• How you try to avoid bug in your code?
• What is Agile methodology? It’s pros and cons?
• How you communicate with different stakeholders while working on some jira?
• How to handle work delivery pressure?
• Any conflict with your teammates?

In the end, I asked feedback he said it was good and I am adapted in agile and overall in this field.

Few questions I forgot from each rounds since they were mostly easy to medium and whole process took around a month.
To me I faced some difficulties in screening and design rounds, other rounds were cakewalk.

After couple of days, I got positive feedback from them and currently I am in negotiation phase.