PayPay Corporation Backend Developer Interview Questions and Answers

Q1. Nodejs promises async await difference
Ans. 
Node.js promises are a way to handle asynchronous operations, while async/await is a syntax for writing asynchronous code in a synchronous manner.
• Promises are objects that represent the eventual completion (or failure) of an asynchronous operation.

• Async/await is a syntactic sugar built on top of promises, making asynchronous code look more like synchronous code.

• Async functions return a promise, which allows you to use ...read more
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Q2. Nodejs architecture eventloop
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Q1. What is structure padding ?
Ans. 
Structure padding is the process of adding empty bytes to a structure to align its data members on memory boundaries.
• Padding is added to ensure that each data member in a structure starts at a memory address that is a multiple of its size.

• Padding is necessary for performance optimization and to prevent memory access violations.

• For example, if a structure has a char followed by an int, padding may be added between them
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Q2. What is translation unit ?
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A translation unit is a source file along with all the headers and source files included in it.
• Translation unit is the smallest unit of compilation in C++.

• It consists of a source file and all the header files and source files included in it.

• Each translation unit is compiled separately before being linked together.

• Translation units help in organizing and modularizing code.

• Example: If a.cpp includes b.h and c.cpp, then t...read more
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Q1. Basic Coding questions
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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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Q1. They asked Oops concepts
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Q2. They asked exception handling
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Aptitude Test based on general

Coding Test Based on backend technologies

Moderate to difficult

Q1. DSA questions based on Dynamic programming
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