Barclays Interview Experience

Round 1: Online Assessment (OA)

1. 1 DSA Coding Question :  LeetCode 3474: Lexicographically Smallest Generated String Solution
2. 1 SQL Query : SQL Questions What I remember is given this  PDF
3. 12 MCQs (Core Subjects + Aptitude)

Round 2 : Technical Interview (~1 hr 20 mins)

1. Introduction

• Started with an introduction.
• Since I mentioned in introduction scoring 100/100 in Maths in 12th, interviewer asked:
  1. To draw a sin curve
  2. Then asked about shifting the curve and changes in equation (sin(x + α))
  3. Asked: What is cosine (basic definition)

2. Core Computer Science

• Compiler Design:
  1. Asked about 6 phases of compiler
  2. I answered partially (syntax, semantic, Lexical Analysis)

3. Database & SQL

• Asked current subjects in syllabus → I mentioned Information Retrieval (I want to divert to my strong area SQL & Database)
• Given a stored procedure and asked to optimize it : Basically it was the use of index (on/off) during insert/update strategy .
• Difference between TRUNCATE vs DELETE
• Explain Concepts Cursor and its usage in your projects.

4. Project Deep Dive

• Asked to explain one of your project.
• Questions on : Collaboard project , Database used (Convex DB)

5. DSA & Complexity

• What is Time Complexity ?
• What is need of Time Complexity ?
• Language used for DSA → C++
• Why C++ for DSA and not Java ?
• Why C++ is faster than Java ?
• Features of Java over C++
• Given a code (heap sort):
  1. Asked to write and analyze
  2. Best, Worst, Average case complexity

7. System Design

• Asked to design a system:
  1. Take user credentials (name, password)
  2. Store with current time
  3. Handle server reboot scenario
• I explained from a database trigger perspective
• Interviewer expected CI/CD pipeline-based solution
• I mentioned I was not familiar with DevOps

9. OS & Networking

• Asked about : SSH and Network Protocols , Basic Linux commands

10. LLD & Design Patterns

• Since I mentioned exploring LLD:
  1. Asked about Design Patterns ( Abstract Factory, Adapter, Bridge, Factory Method, Singleton )
  2. Where I used them in projects

Duration:

Round 3 : Technical Interview + HR  (~45–50 mins)

1. Introduction & Background

• Started with a brief introduction.
• Asked about my experience and technologies I have worked on.

2. Technical Discussion

• Since the interviewer was working on TypeScript, she asked detailed questions:
  1. Difference between interface vs type
  2. Concept of decorators
• Asked : Why have you chosen Next.js & TypeScript for your project?

3. Project Discussion

• All projects were discussed in detail.
• I demonstrated my project using my mobile and explained the complete flow.
• Questions included:
  1. Features implemented
  2. My role in the project

4. Core Concepts

• Explained OOP pillars and where I used them in my project.
• Asked about SOLID principles and their usage in real projects.
• Use of SOLID principles in my projects

5. DSA & Problem Solving

• Asked about my DSA preparation and ratings on Leetcode and Codechef.
• Question:
  1. How to search an element in a Binary Tree , Explain all possible ways
  2. Explained approaches: DFS & BFS
  3. She ask question of mirror image of tree ( Leetcode 101 )
• Performed a dry run of Level Order Traversal code

6. Database & System Design

• Asked to design the database schema of my project:
  • Fields, relationships, foreign keys
  • Draw and Explained ER Diagram (NSS Treasure Project)
• Asked about:
  • ACID properties and how I handled them

7. Extracurricular & Leadership

1. My role as Data Head
2. Explained responsibilities and work
3. Shared experience of managing a team during camps

8. Behavioral & Practical Questions

1. How I handled risks in my project
2. Whether I have learned new technologies under tight deadlines

Duration:

Verdict: Selected ✅

Key Learnings:

• Whatever you mention in your resume, you should know every word in detail.
• Be very strong in your projects (end-to-end understanding)
• Prepare core CS subjects (Compiler, OS, SQL, IR) thoroughly
• Expect cross-questioning and deep discussions
• Have at least basic knowledge of DevOps concepts (CI/CD)
• Be ready to justify technology choices