Freecharge Backend Developer Interview Questions and Answers

Round duration - 90 mins
Round difficulty - Hard

There were questions related to DP and DFS.

 

Q1. 
Trapping Rain Water Problem Statement
You are given a long type array/list ARR of size N, representing an elevation map. The value ARR[i] denotes the elevation of the ith bar. Your task is to determine th...read more
Ans. 
Calculate the total amount of rainwater that can be trapped between given elevations in an array.
• Iterate through the array and calculate the maximum height on the left and right of each bar.

• Calculate the amount of water that can be trapped at each bar by taking the minimum of the maximum heights on the left and right.

• Sum up the trapped water at each bar to get the total trapped water for the entire array.
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Round duration - 60 mins
Round difficulty - Medium

At first, I was asked about the different projects that I have done so far. We had a detailed discussion on the same.
He also checked my OOP concepts

Q1. Can you describe the process of designing an LRU Cache from scratch during your System Design Round?
Ans. 
Designing an LRU Cache involves implementing a data structure that stores a fixed number of items and removes the least recently used item when full.
• Start by defining the data structure for the cache, typically using a combination of a hashmap and a doubly linked list.

• Implement methods for getting and setting key-value pairs in the cache.

• When a new item is added to the cache, check if it exceeds the maximum capacity. I...read more
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Q2. 
Reverse Linked List Problem Statement
Given a Singly Linked List of integers, your task is to reverse the Linked List by altering the links between the nodes.
Input:
The first line of input is an intege...read more
Ans. 
Reverse a singly linked list by altering the links between nodes.
• Iterate through the linked list and reverse the links between nodes

• Use three pointers to keep track of the current, previous, and next nodes

• Update the links between nodes to reverse the list

• Return the head of the reversed linked list
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Q3. 
Middle of a Linked List
You are given the head node of a singly linked list. Your task is to return a pointer pointing to the middle of the linked list.
If there is an odd number of elements, return the ...read more
Ans. 
Return the middle element of a singly linked list, or the one farther from the head if there are even elements.
• Traverse the linked list with two pointers, one moving twice as fast as the other

• When the fast pointer reaches the end, the slow pointer will be at the middle

• If there are even elements, return the one that is farther from the head node

• Handle edge cases like linked list of size 1 or empty list
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Round duration - 60 mins
Round difficulty - Medium

It is HR + Technical round
asked about the Behavioural questions and how you justify yourself in an argument .questions related to current technology.
They gave me feedback on how well I had performed so far and gave me suggestions on what more can I do to further improve myself.

Q1. What is the role of RJ45 in networking?
Ans. 
RJ45 is a type of connector commonly used for Ethernet networking.
• RJ45 connectors are used to connect computers, routers, switches, and other network devices to create a local area network (LAN).

• They are designed to transmit data using twisted pair cables.

• RJ45 connectors have 8 pins and are commonly used in Ethernet networks for both wired and wireless connections.
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Q2. What is the typical power consumption for domestic electrical lines?
Ans. 
The typical power consumption for domestic electrical lines varies depending on the size of the house and appliances used.
• Power consumption can range from 500 to 2000 watts per hour for an average household.

• Larger homes with more appliances may consume more power.

• Energy-efficient appliances can help reduce power consumption.

• Seasonal variations and usage patterns also impact power consumption.

• Electricity bills typically...read more
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Q1. What is your experience regarding job roles and tenure?
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Q2. What is your availability for phone calls?
Ans. 
I am available for phone calls during regular business hours and can make myself available for urgent matters outside of those hours if needed.
• Available for phone calls during regular business hours

• Can make myself available for urgent matters outside of regular hours if needed
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Q1. Onbording experience
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Q2. UPI knowledge and experience
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Q3. Field work knowledge
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Q1. Next Greater Element in an array
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Q2. Question based on Sql inner join
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Round duration - 75 Minutes
Round difficulty - Medium

The round consisted of 2 Coding based based questions.
These question were easy for as I have already done this while preparing.

Q1. 
Flip Equivalent Binary Tree Problem
Determine whether two binary trees, given by their roots 'ROOT1' and 'ROOT2', are flip equivalent. A tree can be transformed into a flip equivalent through any number o...read more
Ans. 
The problem is to determine if two binary trees are flip equivalent after performing flip operations on one of the trees.
• Perform a depth-first search (DFS) on both trees simultaneously

• At each node, check if the values are equal and the left and right subtrees are either both null or both not null

• If the above conditions are met, recursively check the flip equivalence of the left and right subtrees

• If any of the condition...read more
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Q2. 
Split Array Into Increasing Subsequences Problem Statement
You are provided with an integer array ARR of size N sorted in ascending order. Your task is to determine if it is possible to split this array i...read more
Ans. 
The task is to determine if an integer array can be split into one or more increasing subsequences with a length of at least 3.
• Check if the array can be split into increasing subsequences by iterating through the array.

• Keep track of the current subsequence and its length while iterating.

• If the difference between the current element and the previous element is not 1, start a new subsequence.

• If the length of any subseque...read more
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Round duration - 60 Minutes
Round difficulty - Easy

The interview started a bit late as I it to be at 11:30 am but started at 12:15pm So Had to wait. Apart from these the overall experience was great and the interviewer was also kind and had a smiling face.

Q1. 
Ninja and Alternating Largest Problem Statement
Ninja is given a sequence of numbers and needs to rearrange them so that every second element is greater than its neighbors on both sides.
Example:
Input:
...read more
Ans. 
The task is to rearrange the given array such that every second element is greater than its left and right element.
• Iterate through the array and check if every second element is greater than its left and right element

• If not, swap the current element with its adjacent element to satisfy the condition

• Continue this process until the entire array satisfies the condition

• Return 1 if the array satisfies the condition, else re...read more
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Round duration - 30 Minutes
Round difficulty - Easy

10:30 PM 
Interviewer was Cool.

Round duration - 5 minutes
Round difficulty - Easy

At 10:00 am

Q1. DSA Round & Introduction Round
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Q2. DP Question related to subsequence
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Q1. Design Parking Lot
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Q2. Sort Numbers with large file
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Q1. Operation related and work profile and experienced , cash management , computer literacy
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Q2. Managing operations
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Q3. Cash Operation handling , limit of cash , indenting
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Q4. Howto manage team handling
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Q5. Job profileof yourooeration
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