Walmart IN3 | March 2021| Full stack Developer | Bangalore

Interview Experience at Walmart - Full Stack Developer

I was contacted by a consultancy about a potential switch and decided to explore the Full Stack Developer role at Walmart in Bangalore.

First Round: Problem Solving and Backend Discussion

This round started with a general introduction, a discussion about my current project, tech stack, and my familiarity with Java, as I didn't have direct work experience in it.

The technical questions included:

• Three Sum Problem: We had a detailed discussion on how to optimize this problem to achieve an O(n^2) time complexity, moving beyond an O(n^3) solution. The interviewer was very keen on my understanding of big O notation and the fundamentals of calculating various complexities.
• Count Leaves in a Binary Tree: I was asked to count the number of leaves in a binary tree.
• SQL Query Problem: This was a scenario-based question involving two tables, Table1 and Table2, both containing name, loc, and datetime columns. The task was to write a SQL query to select de-duplicated records based on loc, ensuring that for each location, only the record with the highest datetime was returned. While I couldn't completely formulate the query on my own, the interviewer provided assistance, and we arrived at a mutually agreed-upon solution.

Second Round: Problem Solving and Front-end Discussion

This round began with an introduction, focusing on my front-end experience, familiarity with various front-end frameworks, JavaScript, and ES6.

The discussion then moved to several front-end and general programming concepts:

• Trapping Rain Water Problem: I was asked to discuss my approach and provide pseudo-code for this problem.
• Design Patterns: The interviewer asked about design patterns I had used, specifically asking me to explain the Builder pattern with an example.
• Webpack: We discussed what Webpack is and how it functions.
• Dependency Injection: I was asked to explain Dependency Injection.
• Closures: A question about JavaScript closures.
• DOM Manipulation: Discussion around DOM manipulation techniques.
• Virtual DOM Manipulation in React: Specifically, how the Virtual DOM works in React.
• Rendering Cache: A discussion on rendering cache.
• Variable Hoisting: Explanation of variable hoisting in JavaScript.
• Tree Shaking: What tree shaking is and how it's used.
• Web Workers: I was asked about Web Workers. While I wasn't familiar with them, I brought up Service Workers and explained them effectively.
• Web Components: A discussion on Web Components.
• var vs. let: The differences between var and let in JavaScript.
• Functional vs. Object-Oriented Programming: The distinctions between these two programming paradigms.
• Node.js Internal Architecture: How Node.js works internally and handles asynchronous operations.
• React Hooks: Discussion about React Hooks.
• Code Optimization Methods: Various approaches to optimizing code.
• Finally, I was given an opportunity to ask questions to the interviewer.

I am currently waiting for the response from the second round.