WEX Interview Experience

Role - SDE3
Experience - 8 yoe

Round 1 — DSA

There were two coding problems:

Longest Substring Without Repeating Characters
Word Break Problem - Find All Ways to Break

Round 2 — LLD

The question was based on designing a logging and alerting system.

The requirements were roughly:

Logs are written to a file.
Logs can have different severity/types such as INFO, WARNING, and CRITICAL.
There is a configurable rule/threshold for each alert type.
When a configured limit is crossed, a notification should be triggered for the user.
Users can subscribe/unsubscribe to particular alert types.
The system should support different notification types.

The discussion focused on the object-oriented design, interfaces/classes, extensibility, and design patterns that could be used to make the system easy to extend.

Round 3 — HLD

This round started with a deep dive into my previous project. The interviewer asked several questions about the architecture, design decisions, scalability, and challenges in the project.

After that, I was asked to design a system similar to BookMyShow, with particular focus on the seat-booking flow.

A major part of the discussion was around handling multiple users trying to book the same seats simultaneously.

Topics discussed included:

Seat availability
Concurrent booking requests
Preventing double booking
Locking/holding seats
Booking expiration
Database consistency
Handling high traffic during popular events

The interviewer asked several follow-up questions based on the design.

Round 4 — Hiring Manager

The final round was around 30 minutes.

It mainly consisted of:

Basic behavioral questions
Discussion about my experience
Discussion about the company and role

The interviewer also gave an overview of the company, team, and role.