| Founding year | 2006 |
| Company Website | http://www.brainstation-23.com/ |
| Career Website | https://erp.bs-23.com/jobs |
| Technologies Used | Android, IOS, React, React-Native, Odoo, Xamarin, .Net, PHP, Python, Java, AEM, Sitecore, Flutter |
Brain Station 23 is at the forefront of global digital transformation, delivering state-of-the-art technology solutions designed to propel businesses into the future. With expertise spanning software development, cloud computing, enterprise-grade mobile applications, AI and machine learning, and blockchain technology, they offer bespoke solutions that drive innovation and efficiency.
Star Coder is an annual recruitment test for BS23. The program has 5 stages
Online MCQ Exam: Everyone who applies for the program will be given the opportunity to sit for this round. Questions are asked from computer science subjects. The topics generally cover programming, data-algo, OOP, databases, etc. Those who do well in this exam are shortlisted for the next step.
Onsite Exam: This round is onsite, a 2-3 hour written exam. Candidates have to take an online exam on problem solving, data algorithms, databases, etc. No internet access is given for this stage.
Day long Assessment Test: This is an interesting round. There are various events throughout the day. Teamwork, idea generation, fun, etc. It is a lot like a hackathon. Presentations have to be given. It takes place in their office from morning to evening. Candidates are given a scenario and some questions. They have to come up with a solution and present it. The submissions are ERD, wireframe, SQL etc.
Technical Interview: Candidates may be interviewed about the project they developed in Step 3. They may also be asked about problem solving and computer science fundamentals
HR Interview
Client Facing Interview: Sometimes candidates are tasked to conduct a real client facing interview. This stage is not applicable for everyone and only given occasionally.
The information presented here is collected from the LinkedIn post of Abdullah Al Hasan vaiya (with his permission, of course).
The problems presented in this round are fairly basic. The format is multiple choice.
Topics Covered are:
The questions provided here are collected from various online platforms such as Facebook and Glassdoor. No individual candidate has disclosed the questions verbatim.
Mr. Joy is planning to build a web browser. Now he is analyzing requirements for the navigation system of his web browser, which will preserve the browsing history. What is the appropriate data structure to use for the navigation system?
The appropriate data structure to use for the navigation system of a web browser is a Stack. A stack follows the Last In First Out (LIFO) principle, which is suitable for maintaining the browsing history.
In the following code snippet, what does the keyword 'this' refer to
class Employee {
private String name;
public Employee(String name) {
this.name = name;
}
}The keyword 'this' refers to the current instance of the class. In this context, 'this.name' refers to the instance variable 'name' of the current Employee object.
In a bag , there is black and red balls. The ratio of black to red is 3:7 , if we add 20 more black balls to the bag then the ratio becomes 1:2. How many red balls are there?
Let the number of black balls be 3x and the number of red balls be 7x. After adding 20 more black balls, the ratio becomes 1:2. So, the number of black balls is 3x + 20 and the number of red balls is 7x. According to the given condition, (3x + 20) / 7x = 1 / 2. Solving this equation, we get x = 40. Therefore, the number of red balls is 7x = 280.
which of the following is false about RDBMS (Relational Database Management System)?
The false statement about RDBMS is: In RDBMS, a unique constraint prevents null values in a column. A unique constraint ensures that all values in a column are unique, but it does not prevent null values.
A train leaves station A at 7 AM with the speed of 60 kmph, and another train leaves the A station at 8 AM with the speed of 90 kmph..when will the second train catch the first train?
The first train is already 60 km ahead and the second train is faster, so we calculate the relative speed: Relative Speed = Speed of Second Train − Speed of First Train = 90km/h − 60km/h = 30km/h Time = Distance / Relative Speed = 60km / 30km/h = 2hours Final answer = 8:00AM + 2hours = 10:00AM The second train will catch the first train at 10 AM
What will be the output of the following code?
#include <stdio.h>
int main() {
int sum = 7 + 6 / 3 + 14 * 2;
printf("%d", sum);
return 0;
}Division and multiplication have higher precedence than addition. So, the expression will be evaluated as 7 + 2 + 28 = 37
If the area of a rectangular region is equal to the area of a square, then the perimeter of the rectangular must be
In the context of the Software Development Life Cycle (SDLC), which model emphasizes the continuous iteration of the development and testing phases throughout the project, accommodating changes in requirements even late in the development process?
The correct answer is Agile Model. The Agile methodology is a project management approach that involves breaking the project into phases and emphasizes continuous collaboration and improvement. Teams follow a cycle of planning, executing, and evaluating.
Who is most likely to write unit tests in a software development project?
Developers are responsible for writing unit tests to ensure that individual units of code are functioning correctly. Unit tests are typically written to test the functionality of the code.
Once upon a time, a group of detectives were presented with a challenge to identify which of the 1000 candies was poisoned before it caused harm to any living species. They had to act fast, as the poison would take effect within an hour of consumption. The detectives knew they could use test subjects, but they needed to determine the minimum number required to solve the mystery in time. Can you help them find the solution before it's too late?
In the Agile Model, what is the primary purpose of a "sprint"?
In Agile methodology, a "sprint" is a short, time-boxed period where a team focuses on completing a specific set of work, essentially a dedicated cycle within a project where a defined amount of functionality is developed and ready for review.
What does the static keyword mean when used with a method?
When the static keyword is used with a method, it means that the method belongs to the class itself rather than an instance of the class. Static methods can be called without creating an instance of the class.
When we declare a field static, exactly a single copy of that field is created and shared among all instances of that class. Similar to static fields, static methods also belong to a class instead of an object. So, we can invoke them without instantiating the class.
Why are immutable objects often preferred in OOP design?
Immutable objects are often preferred in OOP design because they are thread-safe, meaning they can be shared between multiple threads without the risk of data corruption. Additionally, immutable objects are easier to reason about and can help prevent bugs related to mutable state changes.
You are given an undirected graph with weighted edges. Which algorithm would you use to find the Minimum Spanning Tree (MST)?
We can use Kruskal's algorithm or Prim's algorithm to find the Minimum Spanning Tree (MST) of an undirected graph with weighted edges.
What is the time complexity of searching for an element in a balanced binary search tree?
The time complexity of searching for an element in a balanced binary search tree is O(log n), where n is the number of nodes in the tree.
There are 100 light bulbs and 100 people. Initially, all bulbs are off. Person 1 flips every bulb (1, 2, 3, 4, …). Person 2 flips every 2nd bulb (2, 4, 6, …). Person 3 flips every 3rd bulb (3, 6, 9, …), and so on, until all 100 people have acted. How many people would have flipped bulb number 72?
We need to find the factors of 72 to determine how many people would have flipped bulb number 72. The factors of 72 are 1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, 72. Therefore, 12 people would have flipped bulb number 72.
A circular queue has a size of 5 and currently contains 3 elements. How many more elements can you insert?
We can insert 2 more elements into the circular queue, as it has a size of 5 and currently contains 3 elements.
You are given the head of a circular singly linked list and an integer n. How would you remove the nth node from the end of the list efficiently?
Use two pointer; fast and slow. Move the fast pointer n steps ahead, then move both fast and slow until fast reaches the last node. Delete slow->next by updating slow->next = slow->next->next. Handle edge cases separately.
You are working with a binary search tree (BST) and need to find the lowest common ancestor (LCA) of two nodes, u and v. Which of the following is the most efficient approach for finding the LCA in a BST, assuming no additional balancing is applied?
The most efficient approach is to traverse the BST from the root, moving left if both u and v are smaller, right if both are larger, and stopping when the current node is between u and v (i.e., the LCA). Time Complexity: O(h), where h is the tree height. Provided the tree is balanced, the height is log(n).
What is the next term in the series: 1, 4, 9, 16, 25, __?
The next term in the series is 36. The series represents the squares of natural numbers: 1^2, 2^2, 3^2, 4^2, 5^2, 6^2.
In a many-to-many relationship between two database tables, which of the following is typically used to model the relationship?
In a many-to-many relationship between two database tables, the correct way to model the relationship is by using a junction table (also called a bridge table or associative entity) that contain foreign keys referencing the primary keys of both tables.
Suppose we have two tables:
students(student_id, name, ...)courses(course_id, title, ...).A student can enroll in many courses, and a course can have many students — this is a many-to-many relationship.
We model it with a junction table such as:
enrollments(
student_id -- FK referencing Students
course_id -- FK referencing Courses
)Optionally, this table can include additional attributes (like enrollment_date, grade, etc.).
Given a code, you have to determine which OOP features is not used in the code above?
Which of the option in a given list is NOT a valid SQL data type?
Given a list of statements, which of them is false for dynamic programming?
A game development team is working on a character system where all characters have a fight() method. Characters like Warrior, Mage, and Archer implement this method differently. Which concept ensures the correct method is executed based on the character type?
The concept of polymorphism ensures the correct method is executed based on the character type. Polymorphism allows objects of different classes to be treated as objects of a common superclass.
Read more about Java Polymorphism | W3 Schools
Given a list of situations, In which of them would a stack be most appropriate?
In a network of cities and roads, you are given n cities and m roads between them. Your task is to determine the minimum number of new roads required to ensure that there is a path between every pair of cities. What is the most suitable approach to solve this problem?
The most suitable approach is to create a connected graph using a Union-Find algorithm. The cities will be connected in multiple components. Each city in a component is connected to any other city in the same component using some series of roads. The minimum number of new roads required is the number of components minus one.
Given a graph in figure, What is the shortest path from a point A to point F using BFS?
Given a list of examples, which of them is an example of compile-time polymorphism?
Function overloading is an example of compile-time polymorphism. It allows multiple functions with the same name but different parameters to be defined in a class.
You are given a list of n unique room numbers belonging to guests at a hotel. These numbers are in the range [0, n], but one guest's room number is missing from the list. What is the best possible space complexity for solving this problem?
The best possible space complexity is O(1). We can use the XOR operation to find the missing room number without using additional space. XOR all the room numbers in a variable x. Then XOR x with the range [0, n] and the missing room number will be the result.
Identify the What type of casting is demonstrated in a code segment?
Implicit Casting (Widening Conversion)
int num = 10;
double result = num; // Implicit casting (int → double)Explicit Casting (Narrowing Conversion)
double value = 9.78;
int num = (int) value; // Explicit casting (double → int)Given some figures of graph, identify which is not a bipartite graph?
A bipartite graph is a graph whose vertices can be divided into two disjoint sets such that no two vertices within the same set are adjacent. A graph that contains an odd-length cycle is not a bipartite graph.
What is the purpose of the final keyword in OOP?
The final keyword in OOP is used to restrict the user. It can be used with variables, methods, and classes. When a variable is declared with the final keyword, its value cannot be changed. When a method is declared with the final keyword, it cannot be overridden by subclasses. When a class is declared. with the final keyword, it cannot be subclassed.
Write a SQL query to retrieve the names of all customers who have placed an order with a total value greater than $1000. Orders are in the orders table and customer information is in the customers table.
SELECT customers.name
FROM customers
JOIN orders ON customers.id = orders.customer_id
WHERE orders.total_value > 1000;Given some statements about database keys, which of them is incorrect?
This round is a mixture of coding problems and MCQs. The topics are the same as the online MCQ round. On average, the number of coding problems given are 9-10 and the number of MCQs are around 30.
Given a number n, write a program to reverse the digits of the number.
class Solution {
public:
int reverse(int x) {
int reverse = 0;
while( x ) {
if( reverse > INT_MAX/10 || reverse < INT_MIN/10 ) return 0;
reverse = reverse * 10 + x % 10;
x /= 10;
}
return reverse;
}
};Given a number n, write a program to find if the number is an armstrong number or not.
An Armstrong number is a number that is equal to the sum of its digits, each raised to the power of the number of digits in the number. For example, 153 is an Armstrong number because 1^3+5^3+3^3=153
class Solution {
public:
bool armstrongNumber(int n) {
int n_ = n;
int a = 0;
while( n > 0 ){
int d = n % 10;
a = a + d * d * d;
n = n / 10;
}
if( n_ == a) return true;
else return false;
}
};Write a program to print a string by removing
class Solution {
public:
string removeSpaces(string s) {
string trimmed = "";
bool seenSpace = true;
for(auto c:s){
if (c != ' ') {
result +=c;
seenSpace = false; // Reset space flag
} else if (!seenSpace) { // If it's the first space after a word
trimmed += ' ';
seenSpace = true;
}
}
while( trimmed.size() and trimmed.back() == ' ' ) trimmed.pop_back();
return trimmed;
}
};Write a program which will do the following for i = 1 to N .
class Solution {
public:
void fooBar(int n) {
for( int i = 1; i <= n; i++ ) {
string output = "";
if( i % 3 == 0 ) output += "Star";
if( i % 5 == 0 ) output += "Coder";
if( output != "" ) cout << output << endl;
else cout << i << endl;
}
}
};Given an integer array nums, rotate the array to the right by k steps, where k is non-negative.
class Solution {
public:
void rotate(vector<int>& nums, int k) {
int n = nums.size();
k = k % n;
reverse(nums.begin(), nums.end());
reverse(nums.begin(), nums.begin() + k);
reverse(nums.begin() + k, nums.end());
}
};Given a number n, print its factorial i.e. n!
class Solution {
public:
void factorial(int n) {
if( n < 0 ) return 0;
if( n == 0 ) return 1;
return n * factorial(n-1);
}
};Given an unsorted array of integers nums, return the length of the longest consecutive elements sequence.:
Ex: Input: 5 3 2 1 After Sort: 1 2 3 5 Ans: 3
Bonus: Write an algorithm that runs in O(n) time.
class Solution {
public:
int longestConsecutive(vector<int>& nums) {
if( nums.size() == 0 ) return 0;
sort(nums.begin(), nums.end());
int seq_length = 1;
int max_length = 1;
for(int i = 1; i < nums.size(); i++){
if( nums[i] == nums[i-1] ) continue;
else if( nums[i] == nums[i-1] + 1 ) seq_length++;
else seq_length = 1;
max_length = max(max_length, seq_length);
}
return max_length;
}
};Given two integers N (upto 18 digits) and M(≤100): Digits of the New Number:
Input: 104 2
Output: 3
→104, 140, 410Candidates need to stay in the office from morning to evening. They are presented with multiple tasks throughout the day. Most important of them are
The written exam have 3 segments
It is taken first thing in the morning. Some of them are taken in sheet of papers and some are taken in external or internal websites.
The behavioural tests are quite similar to the ones standardized by Amazon. The situational judgment test (SJT) or behavioral assessment stage evaluates a candidate's decision-making and problem-solving skills in workplace scenarios. Candidates are presented with a situation and two possible responses, selecting their preference on a scale from strongly favoring one option to neutral or favoring the other. This helps employers assess traits like leadership, teamwork, and customer focus. Companies like Amazon use this method to identify candidates who align with their core values and work culture.
A customer reaches out with a complaint about a product they purchased. They are clearly frustrated, but the issue falls outside the company’s usual return policy.
Options:
A) Stick to company policy and explain why you can’t help them.
B) Make an exception to satisfy the customer.
Scale:
1️⃣ Strongly Prefer A 2️⃣ Moderately Prefer A 3️⃣ Neutral 4️⃣ Moderately Prefer B 5️⃣ Strongly Prefer B
A customer reaches out with a complaint about a product they purchased. They are clearly frustrated, but the issue falls outside the company’s usual return policy.
Options:
A) Stick to company policy and explain why you can’t help them.
B) Make an exception to satisfy the customer.
Scale:
1️⃣ Strongly Prefer A 2️⃣ Moderately Prefer A 3️⃣ Neutral 4️⃣ Moderately Prefer B 5️⃣ Strongly Prefer B
You and a coworker are working on a project together. They propose an approach that you don’t fully agree with, but they seem confident it will work.
Options:
A) Trust their judgment and follow their lead.
B) Insist on discussing the approach further before moving forward.
Scale:
1️⃣ Strongly Prefer A 2️⃣ Moderately Prefer A 3️⃣ Neutral 4️⃣ Moderately Prefer B 5️⃣ Strongly Prefer B
Aptitude tests assess a candidate’s problem-solving ability, logical reasoning, numerical skills, and verbal comprehension. These tests are commonly used in hiring to evaluate a candidate's ability to think critically and process information efficiently. They are often timed and include questions on math, logic, patterns, and language. These tests are written or MCQ type questions. On average there are 30 questions like these.
If you had to choose 1 food to eat for the rest of your life, then what would it be? why?
Which actor do you like the most? why?
When do you feel sad the most?
This test is language dependent. You'll be asked to chose a language eg Java, JavaScript, Python etc and the questions will be based on that language. There are about 15 questions in this test.
The topics are from core language features, loop, time complexity, data structures, algorithm etc.
Give a description about your favourite project
One of the tasks is to come up with a solution for a given scenario. The candidates are divided into groups and each group is assigned a mentor. The mentor will guide the group throughout the task. The groups need to present their solution at the end of the day. The presentation includes ERD, wireframe, SQL etc. Each one of the group members needs to present a part of the solution.
Create presentations on a ticket management system
You are to design a system for a ticket management system. There are multiple employees in the system; admin, ticket master, cashier, checker, user. Each employee has different roles. For example, the ticker master can issue tickets. He can also edit or delete a ticket allocation. The cashier collects payment for the tickets. He can also issue ticket. The checker only checks the validity of the tickets. There can be multiple type of tickets based on the seat. Admin can create new type of tickets in the system. An user buys ticket from the system.
The candidates are to present
Each candidate faces yet another interview at the end of the day. This stage is language independent and focues on general software development knowledges. Topics might include git, SDLC, data structures, algorithm etc.
Some situations are given, you'll need to provide which algoritm is best suited for solving the task.
Given some code, you'll need to figure out the time complexity of the code
This round is not present in the Star Coder program every year. But in some years, candidates are asked to submit a project. A scenario is given to the candidates through email. The project is chosen based on the candidates preferences presented in the previous rounds. The project is to be submitted within a week. The projects given are pretty basic, but the candidates are expected to follow best practices.
A sample project scenario is given below:
Create a simple system for a task management system.
Implement additional features like pagination, search, filtering etc
The project will be evaluated based on the best practices followed, code quality, and the features implemented
Use version control to manage the codebase. The codebase should be hosted in a public repository.
Provide a README file with setup instructions, API documentation, and any other necessary information.
Write unit tests for the core logics. Add instructions on how to run the tests.
This round is also language and stack specific. The language is chosen by the candidate during the day long assessment. Some sample questions from Java are given.
What is primitive and non primitive data types? How are they different? When can their values be changed?
Why are strings immutable in Java?
What are the 4 principles of OOP?
What is diamond problem?
Diamond Problem is a problem faced during Multiple Inheritance in Java. This problem occurs when a class inherits from two interfaces that both extend a common interface and define a method with the same name. The ambiguity arises because the class implementing these interfaces does not know which method to call when invoking the method by name.
Does Java support multiple inheritence?
Java doesn't allow multiple inheritance to avoid the complexity and ambiguity associated with it, particularly the "diamond problem," where a class inherits from two classes that have a common ancestor, leading to conflicts in the inheritance of methods.
Read more from Diamonds Aren’t a Developer’s Best Friend: Tackling the Diamond Problem in Java
How does Java tackle the multiple inheritence issue?
Java doesn't allow multiple inheritance to avoid the complexity and ambiguity associated with it, particularly the "diamond problem," where a class inherits from two classes that have a common ancestor, leading to conflicts in the inheritance of methods.
To resolve this ambiguity, you must override the conflicting method in the implementing class and explicitly specify which method you want to use.
interface A {
default void foo() {
System.out.println("A's foo");
}
}
interface B extends A {
default void foo() {
System.out.println("B's foo");
}
}
interface C extends A {
default void foo() {
System.out.println("C's foo");
}
}
class D implements B, C {
@Override
public void foo() {
B.super.foo(); // or C.super.foo();
}
public static void main(String[] args) {
D d = new D();
d.foo();
}
}In this example, the foo method is overridden in class D, and within the overridden method, we explicitly call the foomethod from either B or C using B.super.foo() or C.super.foo().
What features of Spring Boot have you used?
What is indexing in Database?
Describe ACID in RDBMS
ACID is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. Databases that support this are called ACID compliance. The properties are
IMPORTANT
Atomicity, isolation and durability are properties of the database, whereas consistency is a property of the application. The C in ACID was tossed in to make the acronym work. [ref: Martin Kleppmann, Designing Data Intensive Applications]
Some questions might be asked from the projects added in resume. If github repository links are added then interviewer might check those out too.
Suppose you have to build a e-commerce site where you have multiple product listing. In the home page the products have some small information listed. When you click on any single product then full details of the product is shown. How would you design the database and system for this?