Testbook.com Software Engineer Interview Questions and Answers

Q1. Android architecture mvvm mvc kotlin
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Q2. Coroutines flows
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Q1. Explain request lifecycle in rails?
Ans. 
Request lifecycle in Rails involves routing, controller actions, rendering views, and responding to the client.
• 1. Request comes in through the browser or API endpoint.

• 2. Rails router determines which controller and action to route the request to.

• 3. Controller action processes the request, interacts with the model, and prepares data for the view.

• 4. View template is rendered with the data from the controller.

• 5. Response ...read more
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Q2. Code Merge Sort using Ruby
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Implement Merge Sort algorithm in Ruby
• Divide the array into two halves recursively

• Merge the sorted halves back together

• Use a helper method to merge the two halves
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Q1. Question on Binary trees: if symmetric, easy string question using hashmap
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Q2. If we are hosting a live test how to show real time ranking, HLD for this and what algorithms can we use
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Q1. Database schema design for a feature where user can be free, gold, platinum.
Ans. 
Use a user table with a column for user type (free, gold, platinum)
• Create a user table with columns for user ID, name, email, user type

• Use a separate table for user types with columns for type ID and type name

• Establish a one-to-many relationship between user and user type tables

• Example: user table - user_id, name, email, type_id; user_type table - type_id, type_name
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Q1. HLD for live rank dashboard for a live test where millions of users are doing test
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High-level design for a live rank dashboard for a live test with millions of users.
• Use a scalable architecture to handle millions of users concurrently.

• Implement real-time data processing to update ranks dynamically.

• Utilize caching mechanisms to improve performance and reduce load on the database.

• Design a user-friendly interface with intuitive data visualization.

• Include features for filtering, sorting, and searching to
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Round duration - 120 minutes
Round difficulty - Easy

It was a mix of mathematical aptitude, logical ability, and puzzles along with 2 programming questions of easy and medium level. Time was enough and no sectional time was present. 1-2 MCQs on SQL were also present.

This round was immediately followed by an SHL aptitude test which was basically a quick limited time check of your verbal ability and math because many questions were to be done in 1 hour.

Q1. 
Boolean Matrix Transformation Challenge
Given a 2-dimensional boolean matrix mat of size N x M, your task is to modify the matrix such that if any element is 1, set its entire row and column to 1. Specifi...read more
Ans. 
You need to make the modifications in the input matrix.
You do not need to print anything, it has already been taken care of.
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Round duration - 60 minutes
Round difficulty - Easy

It was an online video interview round on HackerEarth with simultaneous code option. It was mostly justifying your resume in the first 15 minutes. After that OOPS was majorly asked. Basics of programming including questions on STL were asked. A class which required inheritance was asked by the interviewer to write. I was helped by the interviewer if i got stuck somewhere, Some questions on implementation of hashmaps and priority queues were also asked. A puzzle was asked which luckily struct to me at that moment.

Q1. What is OOPS concepts.
Ans. 
OOPS concepts refer to Object-Oriented Programming principles like inheritance, encapsulation, polymorphism, and abstraction.
• Inheritance: Allows a class to inherit properties and behavior from another class.

• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Polymorphism: Ability to present the same interface for different data types.

• Abstraction: Hiding the complex implementation detail
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Q2. What is PDO and uses in PHP.
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PDO stands for PHP Data Objects, a database access layer providing a uniform method of access to multiple databases.
• PDO is a PHP extension that provides a data-access abstraction layer.

• It supports multiple database systems like MySQL, PostgreSQL, SQLite, etc.

• PDO helps prevent SQL injection attacks by using prepared statements.

• It allows for error handling and supports transactions.

• Example: $pdo = new PDO('mysql:host=loc...read more
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Asked 3 technical questions on heaps, Ll, treees

2 coding questions with aptitude question(logical aptitude and quantitative aptitude)

This was a Machine Coding. We need to design a system and then they will check our design by running test cases. It was 2.5 hrs long.

Q1. Basic questions on computer core subjects(Deadlock, Networking, Tcp connection, process scheduling etc, DNS Lookup etc)
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Q2. Questions on React, Node and the libraries which I used in my project(My project was a full stack project)
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