I received a call from PayPal HR for an initial telephone interview. Following that, two rounds of interviews were scheduled:

• A DSA and algorithm round.
• A system design (HLD) round.

After clearing these two rounds, a full-stack interview and a technical-managerial round will take place. The entire interview process took two weeks.

First Round: DSA and Algorithms

Basic DSA Concepts

• What is a data structure, and why is it used?

Non-Linear Data Structures

• Explain a non-linear data structure.

Sorting Techniques

• Explain a sorting algorithm.

Divide and Conquer

• Explain the divide and conquer algorithm.

Priority Queue

• Explain priority queues and their use cases.

Deque (Double-Ended Queue)

• What is a deque, and how does it work?

Basic SQL Concepts

WHERE Clause

• What is the use of the WHERE clause?

WHERE vs. HAVING Clause

• Explain the difference between WHERE and HAVING clauses.

Second Round: System Design

After the first round, a HackerRank link is shared for coding with an invite.

Payment Aggregation

Given different payment types and corresponding amounts (e.g., {credit card: 400, UPI: 200}), write a function to return the total amount for each payment type.

Notification System Design

Design a scalable notification system.