Nippon Data Systems Node JS Developer Interview Questions and Answers

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Q1. Programming related questions.
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Q1. DSA round (easy to medium)
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Q1. Technical+ hr round
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Q1. Technical questions.
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Simple question...….. ।।

Q1. Java questions Opps, coding ques
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Q2. Opps Coding । । ।
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Q1. How make a queue using a stack
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To implement a queue using a stack, use two stacks and simulate the queue operations.
• Use two stacks, one for enqueue operation and one for dequeue operation.

• For enqueue operation, simply push elements onto the stack used for enqueueing.

• For dequeue operation, if the dequeue stack is empty, pop all elements from enqueue stack and push onto dequeue stack.

• Then pop from the dequeue stack to simulate dequeue operation.
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Q2. Create a linked list
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A linked list is a data structure consisting of nodes where each node points to the next node in the sequence.
• Create a Node class with data and next pointer

• Initialize a head pointer to null

• Add nodes by updating next pointers

• Traverse the list by following next pointers
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Q1. Lookup vs graphlookup in mongodb
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Lookup is used to perform a left outer join in MongoDB, while graphlookup is used to perform recursive graph traversal.
• Lookup is used to perform a left outer join between two collections in MongoDB.

• Graphlookup is used to perform recursive graph traversal in a collection that contains graph data.

• Lookup can only perform a single level join, while graphlookup can perform multiple levels of traversal.

• Lookup is faster than
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Q2. Count frequency of each character in string
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Use a hashmap to count the frequency of each character in a string.
• Create a hashmap to store characters as keys and their frequencies as values.

• Iterate through the string and update the hashmap accordingly.

• Return the hashmap with character frequencies.
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Q1. Create a rest api all the way from controller to repository using NOTEPAD
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Creating a REST API from controller to repository using NOTEPAD
• Create a controller class with mapping annotations for REST endpoints

• Implement service layer to handle business logic and interact with repository

• Define repository interface with methods for data access operations

• Use Spring Boot for easy setup and configuration

• Test API endpoints using tools like Postman
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Q2. Couldnt write custom mongodb query at repository layer in notepad which rejected my candidature.
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It was ok. I was not able to solve all the questions.

Q1. Remove the last element from a linkedlist
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Q2. Some basic questions on oops dbms and os
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Q1. What is normalization
Ans. 
Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity.
• Normalization helps in minimizing data redundancy by dividing the database into multiple tables.

• It ensures data integrity by avoiding update anomalies.

• Normalization is achieved through a series of rules called normal forms, such as 1NF, 2NF, 3NF, etc.

• Example: In a database, instead of storing customer details i...read more
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Q2. What is reflection
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Reflection is the ability of a program to examine and modify its own structure and behavior at runtime.
• Allows accessing metadata of types and members at runtime

• Enables dynamic instantiation of objects

• Facilitates invoking methods dynamically
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Simple question on maths

Q1. Explain OOPS concept
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OOPS (Object-Oriented Programming) is a programming paradigm based on the concept of objects, which can contain data and code.
• OOPS focuses on creating objects that interact with each other to solve complex problems

• Key principles include encapsulation, inheritance, polymorphism, and abstraction

• Encapsulation ensures that the internal state of an object is hidden from the outside world

• Inheritance allows a class to inherit...read more
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Q2. Coding array questions
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60mintues DSA level coding exam