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PayPal Interview Experience | SDE 1 (On-Campus)
• Difficulty Level : Medium
• Last Updated : 20 Aug, 2020

Round 1(Coding Test): This was a fairly easy round, 2 questions were asked, and we had 2 hrs to solve the questions. The first question was, given a number n, find integral pairs of x,y such that 1/x + 1/y = 1/n!. This question was based on finding divisors using a sieve. The second question was a simple BFS question, given a knight on the chessboard to find whether it can reach a destination cell or not.

Round 2 (Technical Interview 1):  In this round, the interviewer asked some introductory questions about me first and some projects from my resume. Then we moved to solve one question. The question was given an array and a number x, you need to count the number of subarrays in which x is the maximum. For example, in the array [4,1,2,3,1,5] and x=3, the subarrays will be {[1,2,3],[1,2,3,1],[2,3],[2,3,1],[3],[3,1]}. Thus, the count is 6. I gave an O(n^2) approach, the interviewer was satisfied with this approach. So then we moved on to modify the question a bit to having multiple x values in the array. For example, array = [4,1,2,3,1,4,1,3], x=3. After scaling my O(n^2) approach, I finally was asked to optimize it. I optimized the approach to use a two-pointer approach in O(n) (Note this can be done with stacks as well).

Round 3 (Technical Interview 2): This round was pretty similar to the last one. It started with the introduction and then projects from my resume. Then we moved on to solving one question again. This time the question was from DP. The question was min jumps (pretty common question on leetcode, gfg etc). The question for those who don’t know. You are given an array, arr and the i-th element is the maximum jumps you can take from that index you need to find minimum jumps required to go from first to the last index. For example, array = [2,3,1,4,5] the answer is 2 in this array 0 -> 1 -> 4.

Round 4 (Managerial/Technical Interview): This round was not that technical. The interviewer was really nice. This round went for more than an hour for me. We started with my interests and work that I had done, all the projects, and what was the whole process of working on the project. He asked questions in between that were a bit technical about the concepts of OS OOP etc, but no fancy stuff just basic questions to gauge understanding. He explained about the company, its vision, etc. We had good discussions on a lot of things.

PS: My resume was totally ML research-based, no summer intern. So if you are thinking that this is going to be in your way getting a job then you are probably wrong. This won’t really matter, you just need to know what you have worked on and some knowledge about basic CS CDCs.

Important Topics and Subtopics to Remember: Written in order of importance:

1. DSA – Basically all the data structures taught in the DSA course and all the common algorithmic techniques.
2. OOP – Know all the 4 basic concepts really well. Prepare OOP concepts in your preferred language as well. For C++, virtual functions, multiple inheritances, etc. Make sure you understand how these work as well. For JAVA, interfaces, and abstract classes, garbage collection, etc.
3. DBS – Know all the 1NF, 2NF, etc. Questions aren’t asked to normalize a table but the interviewer might ask about the basic concepts so better be prepared. Transactions are not a must but good to know. Know basic SQL queries JOIN, COUNT, etc (For example – Oracle will explicitly ask to write SQL queries).
4. OS – Know the basic concepts, processes, and threads, concurrency, semaphores, and mutex, scheduling algorithms (Won’t be asked but if the interviewer asks to explain any you should know at least the basic ones like FCFS, etc).
5. Networks – Know the basic layers and their devices (OSI model). TCP and its concepts (3-way handshake, etc).

Please see the past interview experiences on geeksforgeeks as well (at least the recent ones) (Yes, they do help). I had very little time (around 10 days) to prepare so most of my DSA wasn’t thorough. So if you have time please try to solve as many problems as possible.

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.  To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.   In case you are prepared, test your skills using TCS, Wipro, Amazon and Microsoft Test Serieses.

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