Lenskart Interview Experience For SDE-2

Telephonic Conversation with HR (5-10 mins)

HR asked a few questions about the current organization – CTC drawn, Expected CTC, tech stack etc.

HR explained the interview process – 3 Technical Rounds

• Technical Round 1 – DSA + CS Fundamentals
• Technical Round 2 – Heavy on Coding (System Design)
• Technical Round 3 – Techno Managerial

Technical Round 1: (DSA + CS Fundamentals) ( 1 hr)

Project Discussion- (20 mins)

The interviewer was a tech lead at Lenskart with around 8-9 years of experience.

We started discussing about the project in my previous company which was in Java and Spring boot tech stack. Various questions around it – Database, Microservices, Deployment etc.

Tip: Be thorough with the project regarding its db schema, why only that design is followed, ways of improvement etc.

Problem-Solving – Similar to ( https://www.geeksforgeeks.org/count-pairs-in-array-whose-sum-is-divisible-by-k/)

Problem:

You are given a list of songs where the song has a duration of time[i] seconds.

Return the number of pairs of songs for which their total duration in seconds is multiple of 60.

Example 1:

Input: time = [30,20,150,100,40]

Output: 3

Example 2:

Input: time = [60,60,60]

Output: 3

I gave the brute force solution, which was an O(n^2) solution. He asked me to optimize it further.

I came up with a hash map approach but it seems like my approach was incorrect. So, I told him that I could not optimize it further.

Then we jump to the next question –

Implement the operations add() and present () of a HashSet in O(1) time.

• I tried implementing it using the hash function and tried to achieve O(1) time.
• There were counter questions on how hashset and hashmap are implemented internally.
• Questions regarding loading factor, collisions etc. were asked.
• I was able to explain all of the concepts.

The last question was based on SQL

In an Employee table, employees belong to three different locations – Bengaluru, Delhi and Chennai. We need to return the count of all the employees belonging to these cities.

I gave the query using group by element, he was satisfied with it.

Conclusion – He asked if I had any questions and then we ended the call.

Overall experience was good, The Interviewer was supportive. However, I knew that due to the lack of problem optimization, I may not be able to get through this round. So, the tip is to revise all the DSA concepts well with the main focus on arrays and strings.

Verdict: Got the rejection mail after half an hour from HR.