Alphamobi.co Senior Backend Developer Interview Questions and Answers

Q1. What is node js and how does it handle concurrency?
Ans. 
Node.js is a runtime environment that allows you to run JavaScript on the server side.
• Node.js is built on the V8 JavaScript engine from Google Chrome.

• It uses an event-driven, non-blocking I/O model that makes it lightweight and efficient for handling concurrent operations.

• Node.js uses the libuv library to handle asynchronous operations and manage event loops.

• Concurrency in Node.js is achieved through event loops and ca...read more
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Q2. 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 and have a predefined schema, while NoSQL databases are document-based, key-value pairs, graph databases, or wide-column stores.

• SQL databases are good for complex queries and transactions, while NoSQL databases are better for hierarchical data storage and real-time web applications.

• Ex...read more
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Q3. Authentication and Authorization.
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Q1. What kind of project you have worked on, project discussion.
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Q2. 3rd Highest number in an array without using any sorting method/algo.
Ans. 
Find the 3rd highest number in an array without sorting.
• Iterate through the array to find the highest, second highest, and third highest numbers.

• Keep track of these numbers as you iterate.

• Return the third highest number once the iteration is complete.
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Q1. What is Node Js
Ans. 
Node.js is a runtime environment that allows you to run JavaScript code outside of a web browser.
• Node.js is built on Chrome's V8 JavaScript engine.

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

• Node.js is commonly used for building server-side applications and APIs.

• It has a large ecosystem of open-source libraries and frameworks, such as Express.js.
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Q2. What is middleware
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Middleware is a software component that acts as a bridge between an application's request and response.
• Middleware functions have access to the request and response objects

• They can modify the request and response objects

• Middleware can be used for tasks like authentication, logging, error handling, etc.
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Q3. What is promise
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A promise is an object representing the eventual completion or failure of an asynchronous operation.
• Promises are used to handle asynchronous operations in JavaScript.

• They can be in one of three states: pending, fulfilled, or rejected.

• Promises can be chained using .then() to handle success and .catch() to handle errors.

• Example: new Promise((resolve, reject) => { setTimeout(() => resolve('Done!'), 1000); });
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Q4. What is promise.all
Ans. 
promise.all is a method in JavaScript that takes an array of promises and returns a single promise that resolves when all of the input promises have resolved.
• Used to handle multiple asynchronous operations at once

• Returns a single promise that resolves when all input promises have resolved

• If any of the input promises is rejected, the returned promise is rejected with the reason of the first rejected promise
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Q5. What is callback
Ans. 
A callback is a function passed as an argument to another function to be executed later.
• Callbacks are commonly used in asynchronous programming to handle tasks that take time to complete.

• They are often used in event handling, timers, and AJAX requests.

• Callbacks can be synchronous or asynchronous, depending on when they are executed.

• Example: setTimeout(callback, 1000) will execute the callback function after 1 second.
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Array,Tree, Behaviour questions 2 hr duration easy-medium

Q1. Array Traversal using topological sort algorithm
Ans. 
Topological sort can be used to traverse an array of strings in a specific order.
• Topological sort is used to order elements based on their dependencies.

• In the context of array traversal, we can use topological sort to determine the order in which strings should be processed.

• For example, if strings represent tasks and their dependencies, we can use topological sort to ensure tasks are executed in the correct order.
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Q2. Right most node in almost complete bst
Ans. 
The rightmost node in an almost complete binary search tree is the last node in the last level of the tree.
• In an almost complete binary search tree, all levels are completely filled except possibly for the last level, which is filled from left to right.

• To find the rightmost node, start at the root and traverse the tree by always going to the right child until reaching the last level.

• The rightmost node will be the last
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Q1. Introduce yourself
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I am a passionate Backend Developer with 5 years of experience in building scalable and efficient web applications.
• 5 years of experience in backend development

• Proficient in programming languages like Java, Python, and Node.js

• Strong understanding of database management systems such as MySQL and MongoDB

• Experience in developing RESTful APIs and microservices

• Familiar with cloud technologies like AWS and Azure
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Q2. Some python programs
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Q1. React questions
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Q2. Nodejs questions
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Q1. Find pairs from list whose is equals to target
Ans. 
Find pairs from list whose sum is equal to target
• Iterate through the list and for each element, check if the target minus the element exists in a hashmap

• If it exists, add the pair to the result list

• If it doesn't exist, add the current element to the hashmap
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Q2. Multiple iNheritance
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An aptitude test is an exam used to determine an individual's skill or propensity to succeed in a given activity.

Q1. Tell me something about yourself?
Ans. 
I am a dedicated and experienced Backend Officer with a strong background in managing backend operations and ensuring smooth functioning of systems.
• Experienced in handling backend operations and maintaining databases

• Proficient in programming languages like Java and Python

• Skilled in troubleshooting and resolving technical issues

• Strong attention to detail and ability to work under pressure

• Excellent communication and team
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Q2. How do you handle stress, pressure, and anxiety?
Ans. 
I handle stress, pressure, and anxiety by practicing self-care, time management, and seeking support.
• I prioritize self-care activities such as exercise, meditation, and hobbies to reduce stress.

• I manage my time effectively by setting realistic goals, breaking tasks into smaller steps, and using productivity tools.

• I seek support from colleagues, mentors, or friends when facing challenging situations.

• I maintain a positiv...read more
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Q3. What are your strengths?
Ans. 
My strengths include strong problem-solving skills, attention to detail, and ability to work well under pressure.
• Strong problem-solving skills: I have a knack for analyzing complex problems and finding effective solutions.

• Attention to detail: I pay close attention to even the smallest details to ensure accuracy and quality in my work.

• Ability to work well under pressure: I thrive in high-pressure situations and can rema...read more
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Q1. Tell me about your self
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Q2. What is your hobbies
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Q3. Why you join our company
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Q4. Tell me about your family
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