HashedIn by Deloitte Interview Questions, Process, and Tips

First round is a basic DS-Algo Round. It was a pen & paper interview. 2 interviewers asked me to write code for some problems such as:
1. You have an unsorted array of 0s and 1s, find the first 1. Different approaches for it.
2. What is setTimeOut in Node.JS?
3. How can you use 2 stacks as an array.
4. You have 2 sorted arrays. Merge them into a single array.

Q1. What are OS processes?
Ans. 
OS processes are instances of a program that are being executed by the operating system.
• Processes are managed by the operating system's scheduler.

• Each process has its own memory space and system resources.

• Processes can communicate with each other through inter-process communication (IPC).

• Examples of processes include web browsers, media players, and text editors.
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Q2. What are threads? What is the purpose?
Ans. 
Threads are lightweight processes that enable multitasking within a single process.
• Threads allow multiple tasks to be executed concurrently within a single process.

• They share the same memory space and resources of the parent process.

• Threads can improve performance by utilizing available CPU resources more efficiently.

• Examples include web servers handling multiple requests simultaneously and video games rendering graphi
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Q3. Why should one use Node.JS?
Ans. 
Node.js is a powerful and efficient server-side JavaScript runtime environment.
• Node.js is fast and scalable, making it ideal for building real-time applications.

• It uses an event-driven, non-blocking I/O model, which makes it lightweight and efficient.

• Node.js has a large and active community, with many useful libraries and modules available.

• It allows for easy sharing of code between the server and client, using JavaScri...read more
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Q4. What is difference between Python and Node.JS?
Ans. 
Python is a general-purpose language while Node.JS is a JavaScript runtime environment.
• Python is used for web development, data analysis, artificial intelligence, and scientific computing.

• Node.JS is used for building scalable network applications and real-time web applications.

• Python is slower than Node.JS in terms of performance.

• Python has a larger standard library than Node.JS.

• Python is easier to learn and has a simp
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Q5. What is the difference between SQL and NoSQL?
Ans. 
SQL is a relational database management system while NoSQL is a non-relational database management system.
• SQL databases are table-based while NoSQL databases are document-based, key-value pairs, graph databases, or column-based.

• SQL databases are structured while NoSQL databases are unstructured.

• SQL databases use SQL (Structured Query Language) for querying and managing data while NoSQL databases use different query lan...read more
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Q6. High Level Design for a Reddit type application
Ans. 
A Reddit-like application for sharing and discussing content
• User authentication and authorization

• Post creation and voting system

• Commenting system

• Subreddit creation and management

• Search functionality

• Real-time updates using websockets
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Q7. What are CORS? How to handle them?
Ans. 
CORS stands for Cross-Origin Resource Sharing. It is a security feature implemented in web browsers to restrict web pages from making requests to a different domain.
• CORS is used to prevent malicious websites from accessing sensitive data from other websites.

• To handle CORS, the server needs to include specific headers in the response to allow the browser to make requests from a different domain.

• The most common header us...read more
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Q8. What is CRFS? The experience around working with it.
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Q1. The final round was with a Senior Manager and he asked about my previous work experience.
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Q2. Low Level Design for Authentication
Ans. 
Low level design for authentication
• Define authentication requirements

• Choose appropriate authentication mechanism

• Design authentication flow

• Implement secure storage of credentials

• Consider multi-factor authentication

• Include error handling and logging
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Q3. Have you managed a team before
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Q4. Architecture Design for an e2e system that takes input from user to the response shown to the user
Ans. 
An e2e system architecture design for user input to response output
• Identify user requirements and define system goals

• Choose appropriate technologies and frameworks

• Design system components and their interactions

• Ensure scalability, reliability, and security

• Test and validate the system before deployment
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