BCG -X Junior Engineer(SWE/Data) Interview Experience

bcg logo
bcg
· Junior Engineer(SWE/Data)
March 20, 2026 · 4 reads

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.

Full Experience

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?

Interview Questions (18)

1.

Missing Number from 1 to n

Data Structures & Algorithms·Easy

Given a short missing number from 1..n numbers, find the missing number.

2.

Aggregate Data from List of Dictionaries

Data Structures & Algorithms·Medium

Given a list of dictionaries, find the aggregate of a particular user ID.

3.

Write SQL Query

Other·Easy

Asked to write an SQL Query with the correct syntax.

4.

Difference between Array and Hashmap

Data Structures & Algorithms·Easy

Explain the difference between an Array and a Hashmap.

5.

JavaScript `preventDefault` Example

Other·Medium

Code an example for JavaScript events using preventDefault.

6.

APIs: GET, PUT, POST, PATCH

System Design·Medium

Explain what APIs are and provide code examples for GET, PUT, POST, and PATCH methods.

7.

What is Local Storage?

Other·Easy

Explain what local storage is.

8.

What are ORMs?

System Design·Easy

Explain what Object-Relational Mappers (ORMs) are.

9.

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 useEffect and useState hooks 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.

📣 Found this helpful? Please share it with friends who are preparing for interviews!

Discussion (0)

Share your thoughts and ask questions

Join the Discussion

Sign in with Google to share your thoughts and ask questions

No comments yet

Be the first to share your thoughts and start the discussion!