Freecharge Web Developer Interview Questions and Answers

Round duration - 45 minutes
Round difficulty - Medium

I applied thorough LinkedIn and got a call from HR for the interview.
I went to their Noida Office.
First round was mainly focused on Javascript fundamentals.
Interviewer was also friendly.

Round duration - 1 hour
Round difficulty - Medium

Second round was after 15 minutes of the first round. The focus of this round was DS & Algorithms.

Q1. 
Find Subarray with Given Sum
Given an array ARR of N integers and an integer S, determine if there exists a subarray (of positive length) within the given array such that the sum of its elements equals S....read more
Ans. 
Given an array and a target sum, find a subarray that sums up to the target sum.
• Iterate through the array while keeping track of the running sum and the starting index of the subarray.

• Use a hashmap to store the running sum and its corresponding index.

• If the running sum - target sum is found in the hashmap, it means a subarray with the target sum exists.

• Return the starting and ending indices of the subarray or [-1, -1]
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Q2. 
Minimum Number of Platforms Required
You are provided with two arrays, AT and DT, representing the arrival and departure times of all trains arriving at a railway station.
Your task is to determine the m...read more
Ans. 
This question asks to find the minimum number of platforms required at a railway station so that no train needs to wait.
• Sort the arrival and departure times arrays in ascending order.

• Initialize a variable 'platforms' to 1 and 'maxPlatforms' to 1.

• Iterate through the arrival and departure times arrays simultaneously.

• If the current arrival time is less than or equal to the current departure time, increment 'platforms'.

• If ...read more
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Round duration - 30 minutes
Round difficulty - Easy

Q1. What JavaScript questions did he ask you during the managerial round, and can you describe the work culture of his team?
Ans. 
The interviewer asked about JavaScript questions and the work culture of the team during the managerial round.
• JavaScript questions related to closures, prototypes, event handling, and asynchronous programming may have been asked.

• Work culture may involve collaboration, innovation, agile methodologies, and continuous learning.

• Examples of work culture could include regular team meetings, code reviews, hackathons, and ment
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Round duration - 15 minutes
Round difficulty - Easy

Coding test consisting of 2 questions. The first was based on a hash set and the second on a string topic.

It was a hacker earth test. The questions i had got was weird and the answer was something along the lines of if(num==2) return "y" else return "N"

Q1. Usual leetcode questions
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Q1. Twitter system design
Ans. 
Twitter is a social media platform that allows users to share short messages called tweets.
• Twitter uses a distributed system architecture to handle high traffic and ensure scalability.

• The system consists of multiple servers for different functions such as user authentication, tweet storage, and search indexing.

• Twitter also uses caching and load balancing techniques to improve performance.

• To handle real-time updates, Tw...read more
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Q2. Api design with filters
Ans. 
API design with filters allows users to retrieve specific data by applying filters to the API request.
• Filters can be applied to different fields in the API request, such as date range, location, or category.

• API design should include clear documentation on available filters and their syntax.

• Filters can be combined to create more complex queries.

• Examples of filter syntax include using operators such as '>', '<', '>=', '<...read more
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Asked to write an in memory SQL database. Time was 1.5 hours. I made the mistake of choosing C++ and writing the code to make it very flexible and extensible. This led to me not being able to complete the task in the given time.
Tip: practice LLD round in a high level language like Python or Typescript. Speed is very important.