Goldman sachs Interview Experience | Software Engineer | Sept 2024

In October 2024, I had the opportunity to interview for a Software Engineer role (3+ years of experience) with the Controllers team at Goldman Sachs. The application was submitted in 2023, and the process involved multiple CoderPad rounds, where I wrote and executed code in Java.

Round 1: HackerRank Test (1.5 Hours)

• Number Checker - Solution Link

Round 2: Problem-Solving CoderPad Round

• First Unique Character in a String - Problem Link

Round 3: DSA 1 and Low-Level Design (LLD)

• Stock Buy and Sell - Max One Transaction - Problem Link
• Stock Buy and Sell - Max Two Transactions - Problem Link

Low-Level Design: Card Payment Processing Service

Task: Design a real-time fault-tolerant payment processing system with multiple banking partners.

Proposed Solution:

System Flow: UI → App1 (Request Handler) → App2 (Bank Integrations/DB) → Cache/Database.

Payment Interface:

interface PaymentProcessor {
 boolean processPayment(String cardID, double amount, String receiverUserID);
}

class PaymentProcessorImpl implements PaymentProcessor {
 BankServicing bankService;

 @Override
 public boolean processPayment(String cardID, double amount, String receiverUserID) {
 validatePayment();
 bankService = getBankService(bankName);
 return bankService.processTransaction(cardID, amount, receiverUserID);
 }
}

Key Challenges Discussed:

Making APIs real-time and fault-tolerant when App2 experiences downtime.

Round 4: DSA 2

Minimum Number of Platforms Required - Problem Link

People Knowing Each Other

Task: Given n people and a list of pairs (a, b) where a knows b, find:

• The number of pairs who do not know each other.
• If x knows y and y knows z, then x also knows z.

Round 5: DSA 3 and Low-Level Design

Lake Counting on a Grid

Task: Write a service to determine the number of lakes present on an island based on any grid coordinate.

Challenge: Unable to come up with a complete approach for this LeetCode Hard problem.

Low-Level Design of Stock Trade Exchange

Final Verdict

I successfully cleared all rounds except Question 1 in Round 5, where I struggled to provide a complete solution. Despite expecting leniency for the complexity of the problem, I was rejected after this round.

Verdict: Disqualified

Takeaways

While I couldn't secure the role, the interview process was a valuable learning experience, especially in tackling real-time system design and complex DSA problems. It highlighted the importance of being well-prepared for edge cases and advanced scenarios.