MongoDB | Summer Internship (On-Campus) | Interview Experience
Summary
I went through four rounds of interviews at MongoDB for a Software Engineering Intern position, cleared the online assessment and the first technical interview, but was ultimately rejected after the techno‑managerial round due to weak CS fundamentals.
Full Experience
MongoDB | Summer Internship (On-Campus) | Interview Experience
Role: Software Engineering Intern Stipend: ₹1.1L/month PPO CTC: 55-59 LPA
Round 1 - Online Assessment
Two coding questions:
- Medium-Hard. A simulation-style problem.
- Easy-Medium. More observation/pattern based than implementation heavy.
I solved the first one completely and the second one partially, and still cleared the round. Around 30 students were shortlisted after this.
Round 2 - Technical Interview 1 (DSA) | 45 mins
One question: LeetCode 1488 - Avoid Flood in The City. Medium-hard in my opinion.
The important part here is that the interviewer cared far more about the approach than the code. They wanted to see me reach the right path with clear reasoning and communicate it well throughout. The interviewer was very chill and gave room to think out loud. I got shortlisted.
Round 3 - Techno-Managerial | 30 mins
This round was split between projects and CS fundamentals.
Projects were grilled deeply - not surface-level questions, but real "why did you do it this way" digging. On fundamentals, they covered OOP, OS, DBMS and system design basics. They explicitly said they expect you to be solid in 3 out of 4. CN wasn't asked since it isn't part of our coursework, and system design was treated as a good-to-have rather than a must.
I hadn't revised my CS fundamentals at all, and that's exactly where I got rejected. This was the round that ended it for me.
Round 4 - HR | 15 mins
8 students made it to this round. From what I heard, it focused on projects again plus general HR questions. 5 offers were made from our college.
Takeaways
- Don't neglect CS fundamentals. The DSA rounds get all the prep attention, but fundamentals are what actually filtered people out here.
- In the DSA round, communication carries more weight than a finished solution. Talk through your thought process constantly.
- Know your projects end to end. Every round after the OA came back to them.
- A partial solve in the OA is not the end - the overall profile matters.
Note: I used AI to polish the writing, but the experience and content are entirely my own.
All the best to everyone interviewing!
Interview Questions (1)
Avoid Flood in The City
You are given an integer array rains where rains[i] indicates the lake that becomes full on day i. If rains[i] == 0, it is a dry day on which you can choose one lake to dry (empty). When a lake becomes full again without being dried first, it floods. Return an array ans where ans[i] = -1 if it is raining on day i, otherwise ans[i] is the index of the lake you choose to dry on that dry day to avoid any flood. If there are multiple valid answers, return any of them. If it is impossible to avoid flooding, return an empty array.