PayPal Interview Experience for SDE II
Round 1(Data Structures & Algorithms): Self Introduction (5 min)
After that, they asked the below
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- Find the element that occurs more than once(https://www.geeksforgeeks.org/array-elements-that-appear-more-than-once/)
- Find all elements that appear more than n/k times in an array.(https://www.geeksforgeeks.org/print-all-array-elements-appearing-more-than-n-k-times/)
- Given 2 nodes, Find LCA with parent pointer. I gave a HashMap based solution to store all paths till 2 nodes starting from root. They wanted a space optimised version, so kept track of parent pointer and checked for ancestors. Similar to intersection point of linked lists (https://www.geeksforgeeks.org/lowest-common-ancestor-in-a-binary-tree-set-2-using-parent-pointer/)
Round 2(System Design & DSA): In-depth description of current project architecture. Various trade-offs to be made.
- Explain Circuit breaker pattern: https://microservices.io/patterns/reliability/circuit-breaker.html
- Internal implementation of HashMap: https://www.geeksforgeeks.org/internal-working-of-hashmap-java/
- Difference between HashMap, HashTable. Which is thread-safe and why?
- Spring vs Spring boot framework(as mentioned in my resume)
- Completable future, lamba expressions, streams in Java 8+
Suggestion: Be very cautious while answering these questions, interviewers have a lot of in-depth knowledge.
Round 3(Managerial Round): This was a tough one. Started with current project and various trade-offs made in my design. Why we use this design pattern in code here. What are the advantages of the underlying architecture (we used: Hexagonal Architecture)
- Merge K sorted lists. (https://www.geeksforgeeks.org/merge-k-sorted-linked-lists/)
- Discuss internal structure of minHeap and maxHeap
- Fastest Sorting Algorithm (https://medium.com/javarevisited/sorting-algorithms-slowest-to-fastest-a9f0e30937b9)
- Given multiple files with different elements how to sort them into one file (without using extra space). https://www.geeksforgeeks.org/external-sorting/
- Design a RESTFul web service that can effectively perform CRUD operations
- Difference between @Controller & @RestController
- WebService versus REST API
- How Spring Boot solves the problems which Spring couldn’t solve
Tip: Do not try to jump directly to code. Discuss with the interviewer first. Do not bluff anything as they are highly knowledgable people.
Round 4(HR & Culture Fit) :
- Work location, Aspirations, Ambitions. Compensation benefits.