Software Engineer Interview Questions Asked by Bangladeshi Companies (2026)

bKash, with over 80 million registered users, runs one of the most structured interview processes in Bangladesh. According to Glassdoor, the process averages 48 days with a difficulty rating of 2.8 out of 5. The written test is the primary filter, followed by technical interviews that emphasize real world problem solving.

Coding Questions (Reported by Candidates)

• • Linked List Duplicate Removal: Given a sorted linked list, remove all duplicate nodes so that each element appears only once. Follow up: what if the list is unsorted?
• • Parenthesis Validation: Given a string containing only the characters (, ), {, }, [, ], determine if the input string is valid. This is LeetCode problem #20.
• • Two Sum: Given an array of integers and a target sum, return indices of the two numbers that add up to the target. Discuss time and space complexity trade offs between brute force O(n²) and hash map O(n) approaches.
• • Linked List Reversal: Reverse a singly linked list iteratively and recursively. Explain the space complexity difference between the two approaches.
• • Find Pairs with Target Sum: Given an array and a target, find all pairs of elements that sum to the target. Handle duplicates correctly.

Database and System Questions

• • Database Concurrency Control: Explain how you would handle concurrent transactions in a banking system. What is pessimistic vs optimistic locking? When would you use each?
• • Deadlock Prevention: How do deadlocks occur in a database? Describe strategies to prevent and detect deadlocks.
• • Database Normalization: Explain 1NF, 2NF, 3NF, and BCNF with examples. When would you intentionally denormalize?
• • REST API Design: Design a RESTful API for a money transfer system. How would you handle idempotency to prevent duplicate transactions?
• • System Design: Design a high availability financial transaction system that handles 80+ million users. Discuss consistency, availability, and partition tolerance trade offs.

OOP and Theory

• • Explain polymorphism with a real world example from a financial system.
• • What is the difference between abstract classes and interfaces? When would you choose one over the other?
• • Explain SOLID principles. Give an example of violating the Open/Closed Principle.
• • What is the difference between == and .equals() in Java?

Optimizely's Dhaka office runs a process that varies significantly by team. According to Glassdoor, the average process takes 27 days with a difficulty rating of 3.5 out of 5. Some teams give take home assignments, others do live coding, and some skip directly to system design interviews.

Take Home Assignment Examples

• • T-shirt Distribution Optimization: Given a set of people with size preferences and a limited inventory of t-shirts, write an algorithm to maximize the number of people who receive their preferred size. Evaluated on correctness, efficiency, code quality, and test coverage.
• • Task Management Reviewer Assignment: Build a system that assigns reviewers to tasks based on workload and expertise. Must be submitted via GitHub with clear documentation and comprehensive test cases.

System Design Questions

• • Internet Banking Backend: Design a system that supports account balance viewing, money transfers between accounts, utility bill payments, transaction history with pagination, and a feature to find the top N users by transaction volume. Bonus: add promo code management and analytics.
• • A/B Testing Platform: Design a feature flagging and experimentation system that can run tests across millions of users with statistical significance calculations.
• • Content Management System: Design a CMS that supports versioning, multi language content, approval workflows, and CDN distribution.

Technical Interview Topics

• • Database design and SQL query optimization
• • Networking fundamentals: HTTP, TCP/IP, DNS, TLS
• • Operating system concepts: processes, threads, memory management
• • OOP principles and design patterns (Factory, Observer, Strategy)
• • API design: REST vs GraphQL trade offs
• • Discussion of projects on your resume

Brain Station 23's annual Star Coder program is one of the most extensive hiring processes in Bangladesh. Based on 5+ documented candidate experiences on Tahanima's Blog, the process can span up to six stages, though not all candidates go through every stage.

Online MCQ Exam Questions (Stage 1)

• • What is the output of a given Java code snippet involving inheritance and method overriding?
• • Which SQL query correctly implements a LEFT JOIN with a GROUP BY clause?
• • What is the time complexity of inserting an element at the beginning of an ArrayList vs a LinkedList?
• • Given a binary tree, what is the order of nodes visited in a preorder traversal?
• • Identify the design pattern used in a given UML diagram.
• • What is the difference between a clustered and non clustered index in SQL?

Onsite Written Exam Questions (Stage 2)

The written exam at the Brain Station 23 office typically includes 30 questions worth 100 marks: a written portion (55%) and an MCQ portion (45%). No internet access is allowed.

• • Problem Solving: Given an array of integers, find the longest contiguous subarray with a sum equal to a target value. Write the solution on paper.
• • Algorithm Implementation: Implement a function to detect a cycle in a directed graph using DFS. Write the pseudocode.
• • Data Structure Completion: Complete an incomplete implementation of a binary search tree (BST) that supports insertion, deletion, and in-order traversal.
• • Database Design: Design an Entity Relationship Diagram for an e-commerce platform with users, products, orders, and reviews.

Day Long Assessment (Stage 3)

• • Design a solution to a given problem using E-R diagrams, UAT diagrams, context diagrams, or flow charts.
• • Work in groups with a mentor (a Brain Station 23 Software Engineer) observing your approach.
• • Present your solution to a panel at the end of the day.
• • Individual problem solving tasks are also assigned during the day.

Therap is one of the most documented companies for interviews, with 8+ candidate stories on Tahanima's Blog. The paper based written test is unusual for a tech company and catches some candidates off guard.

DSA Questions (Reported by Candidates)

• • Stock Trading Profit Maximization: Given an array of stock prices, find the maximum profit you can achieve by buying and selling once. Follow up: what if you can make multiple transactions?
• • Move Zeros: Given an array, move all zeros to the end while maintaining the relative order of non zero elements. Do this in place.
• • Anagram Grouping: Given an array of strings, group the anagrams together. Example: ["eat", "tea", "tan", "ate", "nat", "bat"] should group into [["eat","tea","ate"], ["tan","nat"], ["bat"]].
• • Substring Detection: Check if one string is a substring of another without using built in functions.
• • Binary Tree Comparison: Given two binary trees, determine if they are structurally identical and have the same values.
• • Rotated Sorted Array Search: Search for a target element in a sorted array that has been rotated at some unknown pivot point. Expected time complexity: O(log n).
• • Linked List Operations: Reverse a linked list. Find pairs with a given sum in a doubly linked list.

OOP and Database Questions

• • Explain the four pillars of OOP (encapsulation, inheritance, polymorphism, abstraction) with code examples.
• • What are the ACID properties of database transactions? Give an example of each.
• • Write a SQL query to find the second highest salary from an employee table.
• • Explain indexing in databases. When should you create an index and when should you avoid it?
• • What is the difference between inner join, left join, right join, and full outer join?

HR Viva (Uniquely Thorough)

Therap's HR round is more comprehensive than most companies. It explicitly evaluates:

• • English communication skills (the company serves US clients)
• • Etiquette and professionalism
• • Awareness of current affairs
• • Personal background and academic journey
• • Why you want to work at Therap specifically

Samsung R&D Institute Bangladesh (SRBD) focuses on mobile software, AI, and IoT research. Their interview process reflects the research oriented nature of the work, with a strong emphasis on computer science fundamentals and problem solving efficiency.

Coding Test Questions

• • Graph Shortest Path: Given a weighted graph, find the shortest path from source to all other vertices. Implement Dijkstra's algorithm. What is the time complexity with a min heap?
• • Dynamic Programming: Given a matrix of 0s and 1s, find the largest square sub matrix containing only 1s. Explain the state transition.
• • String Manipulation: Given a string, find the longest palindromic substring. Discuss O(n²) expand around center and O(n) Manacher's algorithm approaches.
• • Array Problems: Find the maximum sum subarray (Kadane's algorithm). Merge overlapping intervals. Find the missing number in an array of 1 to N.

Technical Interview Topics

• • Operating systems: virtual memory, page replacement algorithms, process scheduling
• • C++ specific: smart pointers, RAII, virtual functions, vtable, memory layout of objects
• • Android internals: Activity lifecycle, content providers, broadcast receivers
• • Computer architecture: cache hierarchy, pipeline hazards, branch prediction
• • Data structures: implement an LRU cache, design a hash map from scratch

1. Design an Internet Banking Backend (Optimizely)

Key requirements: account balance viewing, money transfers, bill payments, transaction history, top N users by transaction volume.

• • Data model: Users, Accounts (one user can have multiple accounts), Transactions (double entry bookkeeping), Bills, Payments
• • Concurrency: Use database level locking or optimistic locking for transfers to prevent race conditions
• • Consistency: Financial data requires strong consistency. Use ACID transactions, not eventual consistency.
• • Top N query: Pre compute and cache the top users using a materialized view or a background job, not a real time query on the full dataset
• • Scale considerations: Read replicas for balance queries, write to primary for transactions, message queue for async bill payments

2. Design a Mobile Financial Services System (bKash style)

Key requirements: send money, cash in/out via agents, bill payment, merchant payment, supporting 80+ million users.

• • Transaction processing: Discuss idempotency keys to prevent duplicate transactions during network failures
• • USSD vs app: Many bKash users use USSD (*247#), so the system must support both channels
• • Agent network: 379,000 agents means distributed float management and reconciliation
• • Fraud detection: Real time transaction monitoring with rules engine and ML models
• • Availability: Financial services need 99.99% uptime. Discuss active active data centers and circuit breakers.

3. Design a Ride Hailing Platform (Pathao style)

Key requirements: rider request, driver matching, real time tracking, surge pricing, payment.

• • Location services: Use geohashing or quadtrees for efficient nearby driver queries
• • Matching algorithm: Consider distance, estimated pickup time, driver rating, and acceptance rate
• • Real time updates: WebSocket connections for live location tracking between rider and driver
• • Surge pricing: Supply and demand ratio by geographic zone, updated every few minutes
• • Payment: Pre authorize the estimated fare, settle after trip completion with adjustments

Commonly Asked Behavioral Questions

• • Tell me about a time you disagreed with a team member on a technical decision. How did you resolve it?
• • Describe a project where you had to learn a new technology quickly. How did you approach it?
• • Have you ever missed a deadline? What happened and what did you learn?
• • Why did you choose software engineering as a career? (Cefalo asks this in the MD interview)
• • What do you know about our company and why do you want to work here?
• • Describe a bug that was particularly difficult to find and fix. What was your debugging approach?
• • How do you handle code reviews? How do you give and receive feedback?
• • Tell me about a time you had to explain a technical concept to a non technical stakeholder.
• • What are your career goals for the next 3 to 5 years?
• • Describe your ideal work environment and team culture.

Tips for Behavioral Interviews

• • Use the STAR method: Situation, Task, Action, Result. Structure every answer this way.
• • Prepare 5 to 6 stories from your past experience that can be adapted to different questions.
• • For companies with international clients (Cefalo, SELISE, Optimizely), practice answering in English.
• • Be specific. "I reduced API response time by 40% by adding Redis caching" is better than "I improved performance."
• • Show self awareness. Talking honestly about mistakes and what you learned is more impressive than claiming perfection.

Bangladesh Specific

• • interview-questions-bangladesh (GitHub): 649+ stars, 30+ companies, 350+ documented questions with solutions
• • Tahanima's Blog: 90+ recruitment stories with detailed process descriptions for Therap, Brain Station 23, Cefalo, SELISE, Tiger IT, and more
• • BD Tech Jobs: Browse current openings to identify companies that match your skill set

Practice Platforms

• • LeetCode: Focus on the Top Interview 150 and Blind 75 lists. Most BD company problems come from these sets.
• • HackerRank: Used by Optimizely, Cefalo, and bKash for online assessments
• • Toph: Bangladeshi competitive programming platform with 2,100+ problems
• • NeetCode: Video explanations for common interview problems, organized by pattern

System Design

• • "System Design Interview" by Alex Xu (Volume 1 and 2)
• • "Designing Data Intensive Applications" by Martin Kleppmann
• • ByteByteGo YouTube channel