BCG -X Junior Engineer(SWE/Data) Interview Experience
- Posted
- 20 Mar 2026
Summary
I interviewed for the Junior Engineer (SWE/Data) role at BCG, which involved three rounds covering data structures, algorithms, system design, web technologies, and behavioral aspects.
How it went
BCG takes 3 rounds for the Junior Engineer Role and had two channels for SWE and Data Engineering (Please note this is Data Engineering not Data Science Channel)
Round 1:
Discussion about projects mainly I was given a short missing number from 1..n numbers. Solved it with arithematic progression equation.I was also given a list of dictionaries
wherein I needed to find the aggregate of the particular user id
I was also asked to write an SQL Query with the correct syntax.
Difference Between Array and Hashmap.
Round 2: Grilled on Projects Concentrated Both on SWE and Data Side End
1. JavaScript events code an example for preventdefault.
2. What are APIs code get put post and patch
3. What is localstorage
4. What are ORM
5. Decorator Functions and Generator Function
6. Tricky snippet of Lambda Function and asked output for the same
7. 8 SQL Queries getting tougher each time
8. React useEffect and useState why and when used
9. Database Indexing
10. Project/Internship Discussion on Resume
Round 3: Managerial Round
1.Asked about Past projects
2.Scare Moment in Development if any
3.Weaknesses
4.Team Collaboration situation scenario
5.Condition wherein I have a critical situation and I got assigned some work on Friday. How to handle then?
Questions asked (18)
- 01
Missing Number from 1 to n
Data Structures & Algorithms · Easy
Given a short missing number from 1..n numbers, find the missing number.
- 02
Aggregate Data from List of Dictionaries
Data Structures & Algorithms · Medium
Given a list of dictionaries, find the aggregate of a particular user ID.
- 03
Write SQL Query
Other · Easy
Asked to write an SQL Query with the correct syntax.
- 04
Difference between Array and Hashmap
Data Structures & Algorithms · Easy
Explain the difference between an Array and a Hashmap.
- 05
JavaScript `preventDefault` Example
Other · Medium
Code an example for JavaScript events using
preventDefault. - 06
APIs: GET, PUT, POST, PATCH
System Design · Medium
Explain what APIs are and provide code examples for GET, PUT, POST, and PATCH methods.
- 07
What is Local Storage?
Other · Easy
Explain what local storage is.
- 08
What are ORMs?
System Design · Easy
Explain what Object-Relational Mappers (ORMs) are.
- 09
Decorator and Generator Functions
Other · Medium
Explain decorator functions and generator functions.
- 10
Lambda Function Output Prediction
Other · Medium
Given a tricky snippet of a Lambda Function, predict its output.
- 11
Advanced SQL Queries
Data Structures & Algorithms · Hard
Solve 8 SQL queries, progressively increasing in difficulty.
- 12
React `useEffect` and `useState`
Other · Medium
Explain why and when
useEffectanduseStatehooks are used in React. - 13
Database Indexing Concepts
System Design · Medium
Discuss concepts related to database indexing.
- 14
Discussion on Past Projects
Behavioral
Discuss past projects listed on the resume.
- 15
Scare Moment in Development
Behavioral
Describe any scare moments encountered during development.
- 16
Discuss Weaknesses
Behavioral
Discuss personal weaknesses.
- 17
Team Collaboration Scenario
Behavioral
Describe a team collaboration situation scenario.
- 18
Handling Critical Work on Friday
Behavioral
Describe how to handle a critical situation where work is assigned on a Friday.