LambdaTest Software Development Engineer Interview Questions and Answers

Q1. Resume based questions
Add your answer
Q2. Event loop in nodejs
Ans. 
Event loop in Node.js manages asynchronous operations by executing callback functions when certain events occur.
• Event loop is responsible for handling I/O operations, timers, and callbacks in Node.js

• It allows Node.js to perform non-blocking operations efficiently

• Event loop continuously checks the event queue for new events to execute
Answered by AI
Add your answer
Q3. Javascript es6 questions
Add your answer

Q1. Promises in javascript
Ans. 
Promises in JavaScript are objects representing the eventual completion or failure of an asynchronous operation.
• Promises are used to handle asynchronous operations in JavaScript.

• They can be in one of three states: pending, fulfilled, or rejected.

• Promises can be chained using .then() to handle success and .catch() to handle errors.
Answered by AI
Add your answer

There were 5 question out of which 2 were coding Data Structure problems , 1 was SQL based , 1 was AI based Problem ( Machine Learning ) and 1 was to create UML Diagram.
First Coding question was pretty easy , other one was kinda tough , UML Diagram was also easy and SQL query was of moderate level.

Q1. There were MCQs related to DSA and coding questions.
Add your answer

Two questions to be solved in 1 hr.

Q1. Basic DSA and 3 coding ques
Add your answer

Q1. Resume based and coding
Add your answer

2 Leetcode Medium questions on hackerrank

Q1. Kadane algorithm based question
Add your answer
Q2. Leetcode medium
Add your answer
Q3. Resume based questions
Add your answer

Q1. Probability question math problem
Add your answer
Q2. Puzzle to solve
Add your answer
Q3. AI based question
Add your answer
Q4. 1 question to solve Leetcode medium
Add your answer

Q1. They asked to design a database table
Add your answer

Round duration - 180 minutes
Round difficulty - Hard

The test link had 3 days expiry so I could attempt test anytime. It was conducted on doselect.com

Q1. 
Equilibrium Indices in a Sequence
You are given an array/list named 'SEQUENCE', which consists of 'N' integers. The task is to identify all equilibrium indices in this sequence.
Explanation:
An equilibr...read more
Ans. 
The task is to find the equilibrium indices of a given sequence, where the sum of elements at lower indices is equal to the sum of elements at higher indices.
• Iterate through the sequence and calculate the total sum of all elements

• Initialize a left sum and right sum as 0

• For each index, update the left sum and right sum and check if they are equal

• If they are equal, add the index to the equilibrium indices

• Return the equil
Answered by AI
Add your answer

Round duration - 60 minutes
Round difficulty - Medium

Video interview round wherein I was asked to wrote code for the problem statements given by the interviewer. The problems were mainly focused on advanced JS concepts like asynchonous progamming, timers, closures, and data structure problems around arrays, sets, linked list etc.

Q1. 
Rearrange Linked List Problem Statement
Given a singly linked list in the form 'L1' -> 'L2' -> 'L3' -> ... 'Ln', your task is to rearrange the nodes to the form 'L1' -> 'Ln' -> 'L2' -> '...read more
Ans. 
The task is to rearrange the nodes of a singly linked list in a specific order without altering the data of the nodes.
• Iterate through the linked list to find the middle node using the slow and fast pointer technique.

• Reverse the second half of the linked list.

• Merge the first and reversed second half of the linked list alternatively to get the desired order.
Answered by AI
Add your answer

Round duration - 30 minutes
Round difficulty - Easy

This was the last round with HR wherein they judged cultural fit and there was discussion on things like my expectations v/s their expectations etc.

Round duration - 30 minutes
Round difficulty - Easy

This round mainly consisted of some questions on advanced JS topics like Execution Context, Callback queue, Micro task queue, Promises, etc.

Round duration - 60 minutes
Round difficulty - Medium

This round was more technical compared to the previous one. The interviewer was a senior developer. If questions were not answered, answers would be given/explained.

Q1. What are some aggregate operators in MongoDB?
Ans. 
Aggregate operators in MongoDB are used for data aggregation and manipulation.
• Some aggregate operators in MongoDB include $sum, $avg, $min, $max, $push, $addToSet, $first, $last, $project, $match, $group, $sort, $limit, $skip.

• Example: db.collection.aggregate([{$group: {_id: '$field', total: {$sum: '$value'}}}])
Answered by AI
Add your answer

Round duration - 30 minutes
Round difficulty - Easy

This round was mainly to assess my experience level, roles, and responsibilities from my previous company. Salary negotiations also happened here.