Freecharge Interview Questions, Process, and Tips

Q1. Explain Virtual Dom
Ans. 
Virtual DOM is a lightweight copy of the actual DOM, used for efficient updates and rendering in React applications.
• Virtual DOM is a concept in React where a lightweight copy of the actual DOM is created and updated in memory.

• When changes are made to the state of a component, React compares the virtual DOM with the actual DOM and only updates the necessary parts, minimizing performance impact.

• This process of updating t...read more
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Q2. Explain New Features in ReactJS
Ans. 
ReactJS has introduced new features like Hooks, Context API, Suspense, and Concurrent Mode.
• Introduction of Hooks allows functional components to have state and lifecycle methods.

• Context API provides a way to pass data through the component tree without having to pass props down manually at every level.

• Suspense enables components to suspend rendering while waiting for something to load, like data from an API.

• Concurrent ...read more
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Q3. Explain High Order Components using the example
Ans. 
High Order Components are functions that take a component and return a new component with additional functionality.
• HOCs are used to share code between components.

• They can be used for adding authentication, logging, or other functionalities to components.

• Example: a HOC that adds a loading spinner while data is being fetched.
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Q4. Explain the reducer method in js using the example
Ans. 
Reducer method in JavaScript is used to manage state changes in applications by taking the current state and an action as input and returning a new state.
• Reducer function takes two parameters - the current state and an action

• It then determines how the state should change based on the action type

• The reducer function returns a new state based on the action type
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The first round is an aptitude assessment that consists of coding questions focused on dynamic programming, as well as medium to hard level aptitude and reasoning questions.

The second round focuses on coding and consists of data structure and algorithm questions related to arrays, linked lists, basic Java concepts, strings, and project-based questions from the resume.

The third round also consists of coding, which includes challenging data structures and algorithms questions based on graphs, trees, multithreading, and difficult SQL-based questions.

Q1. What are your short-term and long-term goals?
Ans. 
My short-term goal is to enhance my skills in backend development and contribute effectively to the team. My long-term goal is to become a lead developer and work on innovative projects.
• Short-term goal: Improve backend development skills

• Short-term goal: Contribute effectively to the team

• Long-term goal: Become a lead developer

• Long-term goal: Work on innovative projects
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Q2. How do you approach solving a large problem within a limited timeframe?
Ans. 
I break down the problem into smaller tasks, prioritize them, and focus on the most critical aspects first.
• Break down the problem into smaller, more manageable tasks

• Prioritize tasks based on importance and impact

• Focus on critical aspects first to ensure progress

• Regularly reassess and adjust the plan as needed
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Q1. How to write docker file
Ans. 
A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image.
• Start with a base image using the FROM keyword

• Use the RUN keyword to execute commands in the container

• Use the COPY keyword to add files from the host machine to the container

• Use the CMD keyword to specify the command to run when the container starts
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Q2. Explain file system in linux
Ans. 
File system in Linux organizes and manages data on storage devices.
• File system controls how data is stored, accessed, and managed on storage devices.

• Linux uses a hierarchical file system structure with directories and files.

• Common file systems in Linux include ext4, XFS, and Btrfs.

• File permissions in Linux determine who can read, write, or execute files.

• Mounting and unmounting drives allows access to different file sys
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Q3. Few Linux commands
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Q4. Kubernetes question
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Q1. Kubernetes case based question
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Q2. Linux scripting
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Leetcode medium and hard

zigzag traversal of BT
merge K sorted Linked List

Q1. Focussed mainly on Java, Spring and HLD
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Q1. LLD of booking system, designing a thread safe array blocking queue
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Q1. Normal salary discussion
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Q1. Longest Consecutive Sequence
Ans. 
Find the length of the longest consecutive elements sequence in an array.
• Sort the array to ensure consecutive elements are adjacent

• Iterate through the array and keep track of the current consecutive sequence length

• Update the longest consecutive sequence length as you iterate
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Q2. Core Java Questions
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Q1. Executor Service and it's code
Ans. 
Executor Service is a framework provided by Java for managing and executing asynchronous tasks.
• Executor Service allows you to easily create and manage threads for executing tasks.

• It provides a way to control the number of threads used for executing tasks, which can help prevent resource exhaustion.

• You can submit tasks to an Executor Service using methods like execute() or submit().

• Executor Service can be used to execut...read more
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Q2. Core Java and Spring boot questions
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Q1. Design patterns
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Q2. Core Java questions
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The aptitude test was medium level.

Q1. Array - Pair Sum - Return pair of the sum from arrays
Ans. 
Find pairs in array that sum up to a given target value.
• Iterate through the array and store each element in a hash set.

• For each element, check if the target value minus the current element exists in the hash set.

• Return the pair of elements that sum up to the target value.
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Q2. Check if two strings are anagram of each other
Ans. 
Check if two strings are anagram of each other
• Create character count arrays for both strings

• Compare the character count arrays to check if they are equal

• Example: 'listen' and 'silent' are anagrams
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Q1. Number of subset
Ans. 
Calculate the number of subsets of a given set
• The number of subsets of a set with n elements is 2^n

• Include the empty set and the set itself in the count

• For example, a set with 3 elements will have 2^3 = 8 subsets
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Q2. Remove kth node from end
Ans. 
Remove the kth node from the end of a linked list.
• Use two pointers, one to traverse the list and another to keep track of the kth node from the end.

• Once the first pointer reaches the end, the second pointer will be at the kth node from the end.

• Adjust the pointers to remove the kth node.
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Q1. Whatsapp low level design
Ans. 
Whatsapp low level design involves messaging, encryption, media sharing, and user authentication.
• Use end-to-end encryption to secure messages

• Implement message queues for real-time message delivery

• Allow media sharing through file transfer protocols

• Use OAuth for user authentication and authorization
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Q2. Lru implemention
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