MongoDB SDE (Software Development Engineer) Interview Questions and Answers

Q1. Hashmap implementation
Ans. 
Hashmap is a data structure that stores key-value pairs and provides constant time complexity for insertion, deletion, and retrieval.
• Hashmap uses hashing function to map keys to indices in an array

• Collisions can occur when two keys map to the same index, which can be resolved using separate chaining or open addressing

• Java implementation: HashMap map = new HashMap<>()
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Q2. Server and environment
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Q3. Differentce Between een Spring boot,spring
Ans. 
Spring is a framework while Spring Boot is a tool that simplifies Spring application development.
• Spring Boot provides auto-configuration and embedded servers.

• Spring requires more configuration and setup.

• Spring Boot is opinionated and follows 'convention over configuration'.

• Spring Boot reduces boilerplate code.

• Spring Boot is ideal for microservices and standalone applications.
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Q4. Type of conttoler in spring and type of annotations
Ans. 
The type of controller in Spring is @Controller and the type of annotations are @RequestMapping and @ResponseBody.
• @Controller is used to mark a class as a Spring MVC controller.

• @RequestMapping is used to map a URL to a method in a controller.

• @ResponseBody is used to indicate that the return value of a method should be serialized and returned as the response body.
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Q5. What is junkins why we use
Ans. 
Junkins is not a known term in software engineering.
• Junkins is not a term used in software engineering.

• It is possible that the interviewer misspoke or meant to ask a different question.

• It is important to clarify any confusion or misunderstandings during an interview.
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Round duration - 90 Minutes
Round difficulty - Medium

It was an online technical round. There were around 20 MCQs and two coding questions. The round had an login window of 30 minutes. One coding question was of the level leetcode medium and the other was leetcode hard.

Q1. 
Search in a Row-wise and Column-wise Sorted Matrix Problem Statement
You are given an N * N matrix of integers where each row and each column is sorted in increasing order. Your task is to find the positi...read more
Ans. 
Given a sorted N * N matrix, find the position of a target integer X.
• Iterate over each row and column to search for the target integer

• Utilize the sorted nature of the matrix to optimize the search process

• Return the position of the target integer if found, else return -1 -1
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Q2. 
Euler’s Totient Function Problem Statement
Given an integer N, your task is to determine the count of integers between 1 and N (inclusive) that are coprime to N.
Input:
The first line contains an intege...read more
Ans. 
Euler's Totient Function calculates count of integers coprime to N between 1 and N.
• Implement Euler's Totient Function to calculate count of coprime integers to N.

• Use the formula: phi(N) = N * (1 - 1/p1) * (1 - 1/p2) * ... * (1 - 1/pk) where p1, p2, ..., pk are prime factors of N.

• Example: For N = 9, phi(9) = 9 * (1 - 1/3) = 6.
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Round duration - 60 Minutes
Round difficulty - Medium

It was a technical + HR round. The interview panel consisted of two technical guys and one person from HR.

Q1. 
Sort Array of Strings Problem Statement
Given an array of strings ARRSTR[] of size N, and a character C, your task is to sort the ARRSTR[] array according to a new alphabetical order that starts with the ...read more
Ans. 
Sort an array of strings based on a new alphabetical order starting with a given character.
• Iterate through the array of strings and compare each string with the given character to determine the new order.

• Implement a custom comparator function to sort the strings based on the new alphabetical order.

• Use built-in sorting functions in programming languages like Python, Java, or C++ to efficiently sort the array.
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Q2. Can you explain the pillars of Object-Oriented Programming (OOP)?
Ans. 
The pillars of OOP are Inheritance, Encapsulation, Abstraction, and Polymorphism.
• Inheritance allows a class to inherit properties and behavior from another class.

• Encapsulation restricts access to certain components of an object, protecting its integrity.

• Abstraction hides complex implementation details and only shows the necessary features.

• Polymorphism allows objects to be treated as instances of their parent class, ena
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