40+ Freecharge Interview Questions and Answers

My favorite app is Spotify.

• Pros: Wide variety of music genres and artists available, personalized recommendations, user-friendly interface.

• Cons: Limited offline listening for free users, occasional ads interrupting music playback.

Use an additional stack to keep track of the minimum value at each step.

• Create a stack to store the actual values.

• Create another stack to store the minimum value at each step.

• When pushing a new value, compare it with the top of the minimum stack and push the smaller value.

• When popping a value, also pop from the minimum stack.

• To get the minimum value at any step, simply peek at the top of the minimum stack.

The interviewee was asked about linked lists, finding the median of two sorted arrays, and printing the left view of a tree.

• For linked lists, the interviewee should be familiar with the basic operations such as insertion, deletion, and traversal.

• To find the median of two sorted arrays, the interviewee should know how to merge the arrays and find the middle element(s).

• Printing the left view of a tree involves traversing the tree and printing the leftmost node at each level.

The payment device will be a compact and secure device that accepts multiple payment methods.

• The device will have a touch screen display for easy navigation.

• It will accept payments through NFC, EMV, and QR codes.

• The device will have a built-in camera for scanning QR codes.

• It will have a biometric authentication feature for added security.

• The device will have a rechargeable battery for portability.

• It will have a receipt printer for generating receipts.

• The device will have a sl...read more

I will establish clear communication channels and facilitate regular meetings to ensure alignment and collaboration.

• Establish clear communication channels

• Facilitate regular meetings

• Encourage open communication and active listening

• Ensure alignment and collaboration

• Address any conflicts or misunderstandings promptly

Designing a high scale Multithreaded system requires careful consideration of thread synchronization, load balancing, and resource management.

• Identify the critical sections of code that need to be synchronized

• Choose an appropriate synchronization mechanism such as locks or semaphores

• Implement load balancing to distribute work evenly across threads

• Use thread pools to manage resources and limit the number of threads created

• Consider using asynchronous programming techniques to r...read more

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

Find the first non-repeating character in a string

• Create a hashmap to store the frequency of each character in the string

• Iterate through the string and check the frequency of each character

• Return the first character with frequency 1

To remove the nth node from the end of a linked list, we can use a two-pointer approach.

• Use two pointers, one moving n steps ahead of the other

• When the first pointer reaches the end, the second pointer will be at the nth node from the end

• Adjust the pointers to remove the nth node

Finding the stock price with maximum profit.

• Calculate the difference between each day's stock price and the minimum stock price seen so far.

• Find the maximum difference calculated in the previous step.

• The maximum difference is the maximum profit that can be made.

• Add the maximum difference to the minimum stock price to get the stock price with maximum profit.

Print even and odd numbers using different threads

• Create two threads, one for printing even numbers and one for printing odd numbers

• Use synchronization mechanisms like mutex or semaphore to ensure proper ordering of output

• Example: Thread 1 prints even numbers (2, 4, 6, ...) and Thread 2 prints odd numbers (1, 3, 5, ...)

To increase engagement in social media handles, focus on creating valuable content, using interactive features, and engaging with your audience.

• Create valuable and relevant content that resonates with your audience

• Use interactive features like polls, quizzes, and live videos to encourage participation

• Engage with your audience by responding to comments and messages, and asking for feedback

• Collaborate with other brands or influencers to reach new audiences

• Post consistently and ...read more

To count the number of zeroes at the end of an array.

• Loop through the array from the end and count the number of zeroes until a non-zero element is encountered.

• Use a while loop to keep dividing the last element by 10 until it is not divisible by 10 to count the number of zeroes.

• If the array is sorted in non-increasing order, use binary search to find the last non-zero element and subtract its index from the length of the array.

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.

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

Designing an Uber app involves creating a user-friendly interface, integrating GPS tracking, payment processing, and driver management.

• Research user needs and preferences

• Create a simple and intuitive interface

• Integrate GPS tracking for accurate location-based services

• Implement secure payment processing

• Develop a driver management system

• Test and refine the app based on user feedback

Code to move 0's to extreme right position in an array of strings

• Iterate through the array and move all 0's to the end of the array

• Use two pointers approach to swap elements

• Example: Input array ['1', '0', '3', '0', '5'], Output array ['1', '3', '5', '0', '0']

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

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 execute tasks in parallel, improving performance in multi-thread...read more

Design a flight booking system for easy and efficient booking process.

• Allow users to search for flights based on destination, date, and number of passengers.

• Provide options for users to select preferred flight times, airlines, and seating preferences.

• Include secure payment processing for booking confirmation.

• Implement a user-friendly interface with clear instructions and easy navigation.

• Offer features like flight status updates, booking management, and customer support.

• Integr...read more

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.

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

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

Search for target element in a rotated sorted array.

• Use binary search to find the pivot point where rotation happens.

• Divide the array into two subarrays and perform binary search on the appropriate subarray.

• Handle cases where the target element is on the left or right side of the pivot.

Sort array of cards in red, blue, green colors.

• Use a custom sorting function to sort the array based on color order.

• Assign a numerical value to each color (e.g. red: 0, blue: 1, green: 2) and sort based on these values.

• Implement a sorting algorithm like bubble sort or quicksort to rearrange the array based on color order.

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.

Convert an array of strings to a LinkedList

• Create a new LinkedList

• Iterate through the array and add each element to the LinkedList

Design a transaction system Bank Wallet.

• Implement user authentication and authorization for secure transactions

• Allow users to deposit, withdraw, and transfer funds

• Provide transaction history and balance updates

• Implement security measures such as encryption and two-factor authentication

LRU cache is a data structure that stores the most recently used items, discarding the least recently used items when full.

• Use a LinkedHashMap to store key-value pairs with access order

• Override removeEldestEntry method to limit the size of the cache

• Update the access order of items when they are accessed

LRU cache is a data structure that stores the most recently used items, discarding the least recently used items when full.

• Use a doubly linked list to keep track of the order of items based on their usage.

• Use a hashmap to quickly access items in the cache.

• When an item is accessed, move it to the front of the linked list to mark it as the most recently used.

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

The question is asking about the normal infection arc in cartoons and providing a briefing on it.

• Normal infection arc in cartoons typically involves a character getting sick or infected with a virus or bacteria.

• The character may exhibit symptoms such as sneezing, coughing, or feeling unwell.

• Other characters may try to help the infected character by providing remedies or seeking medical help.

• The infection arc usually resolves with the character getting better and returning to ...read more

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 systems on Linux.

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

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 Mode allows React to render multiple components at the sam...read more

Handling challenges involves staying calm, analyzing the situation, seeking help if needed, and taking decisive action.

• Stay calm and composed to think clearly

• Analyze the challenge to understand its root cause

• Seek advice or help from colleagues or mentors

• Take decisive action to address the challenge effectively

To convert active sales, focus on building relationships, providing value, and addressing customer needs.

• Build strong relationships with customers to increase trust and loyalty

• Provide value through personalized solutions and excellent customer service

• Address customer needs by understanding their pain points and offering tailored solutions

• Follow up regularly to maintain engagement and address any concerns

• Offer promotions or discounts to incentivize purchases

Program to read a file in backend development

• Use a programming language like Python, Java, or C++ to open and read the file

• Use file handling functions to read the contents of the file

• Handle exceptions for file not found or permission issues

• Close the file after reading to free up system resources

Object-oriented programming paradigm that focuses on objects and classes for code organization and reusability.

• Encapsulation: Bundling data and methods that operate on the data into a single unit (object)

• Inheritance: Ability of a class to inherit properties and behavior from another class

• Polymorphism: Ability to present the same interface for different data types