Paytm

Role: Senior Software Engineer

College: Not Specified

Interview Date: October 2023

Interview Type: Not Specified

Result: Offer

Difficulty: Medium-to-Hard

Rounds: Hackerrank Online Assessment + 2 Technical Rounds

Topics Asked: Data Structures, Algorithms (Kadane's algorithm, rainwater trapping problem, flattening multilevel linked list, Longest Common Subsequence), Design Patterns, System Design (CAP theorem, consistent hashing), Project Discussion

Experience:

The candidate had 3 years of experience in the tech industry and received an invitation from Paytm for the Senior Software Engineer position.

Hackerrank Online Assessment: The initial stage was an online assessment. It comprised four medium-to-hard data structure and algorithm questions, along with 5-6 MCQs, all to be tackled within a 90-minute frame. The candidate managed to crack all of them.

Round 1 (Delving Deep into Algorithms & Design): Two medium-tier algorithm questions were given:

• One based on the renowned Kadane's algorithm.
• The classic rainwater trapping problem.

The candidate efficiently solved both. The discussion then seamlessly transitioned into design patterns, exploring different combinations. Core concepts of system design like the CAP theorem and consistent hashing were also touched upon.

Round 2 (From Introductions to Intricate Algorithms): This round began with a brief introduction followed by a discussion on past projects, aligning experiences with Paytm's aspirations. Then came two data structure and algorithm questions:

• Flattening of a multilevel linked list.
• A variation of the Longest Common Subsequence (LCS).

The candidate approached both problems methodically, demonstrating systematic thinking.

The journey concluded with a positive outcome, leading to an offer.