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Paytm Interview Experience for SDE (On-Campus 2020)
• Difficulty Level : Medium
• Last Updated : 25 Feb, 2021

Round 1 (Online Coding round): This round consists of 3 Coding questions that have to be solved in a total of 70 min.

Smallest subarray with sum greater than a given value. (https://www.geeksforgeeks.org/minimum-length-subarray-sum-greater-given-value)

1. Linkedlist question where we had to reverse both halves of the list, about the mid-point. If the list is of odd length, then the position of the middle node should not change. Finally, return the modified list.   Note: Do not create a new list, modify the existing list.
2. Tree question where we had to implement a function to return the total number of nodes in subtree if tree2 is a subtree of tree1 else return 0. tree2 is said to be a subtree of tree1 if the root node of tree2 is present in tree1 and all its descendants are the same as in tree1. (https://www.geeksforgeeks.org/check-binary-tree-subtree-another-binary-tree-set-2)
```Node:
Return -1 if tree1 or tree2 is empty.Return 0 if tree2 is not a subtree of tree1.```

The platform for the coding round was cocubes. I was able to solve all 3 questions and called for the interviews. Candidates with 2 questions were also called for interviews. Total 82 candidates were shortlisted for the interviews. All interviews are online.

Round 2 (Technical Interview, around 1 hour 10 min): Initially, we both greeted each other. We had a little formal conversation at the start of the interview regarding my past education and work experience (I had 2 years of work experience). After that, he straight jumped up to DSA questions which are as follows –

• https://www.geeksforgeeks.org/a-boolean-matrix-question/
• Print path between any two nodes in a Binary Tree

I had already solved the 2nd question and known 2-3 approaches to it but I have not encountered with 1st question. I took some time to break down the 1st question and was able to find O(n) space solution with which he was quite satisfied. He told me that there is an O(1) space solution as well for 1st problem.   He made me feel comfortable by providing some hints and after thinking for some time, I provided him O(1) space solution.

After the DSA part,   he plunged into java questions which I had mentioned in my resume. He asked me to rate myself out of 10 in java so I gave 6/10.

He asked some basic java programming-related Questions such as –

• Difference between c++ and java
• What is JVM and how does it work?
• Why java is platform-independent?
• What are Abstract class and Interfaces in java and how do they differ?
• What is Maven? – Here I went completely blank (I haven’t worked with Maven). He assisted by telling me, why it is used in java projects (mostly preserving dependencies). Now he framed a question from here, he told me how would you find conflicting dependencies if there are multiple .jar files and there are dependencies among .jar files. For example, a.jar depends on b.jar, b.jar depends on c.jar, and so on. I was well aware of topological sorting and how it is used for dependency preserving so before jumping straight to the solution, I asked him whether dependencies are involved in the cycle or not. His reply (no cyclic dependencies) forced me to go with topological sorting and everything went with the flow afterward.

All the codes had to be written on online google docs. I was called for Round 2.

Round 3 (Technical Interview, around 1 hour): We introduced each other at the start of the interview.

• He asked me to briefly explain any one projects which I enjoyed the most.
• Then he asked one or two SQL queries. I was not able to solve one of the queries.
• https://www.geeksforgeeks.org/print-left-view-binary-tree/
• https://www.geeksforgeeks.org/queue-using-stacks/