Freecharge SDE Intern 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. 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
Ans. 
Find the next greater element in an array for each element
• Iterate through the array and for each element, find the next greater element

• Use a stack to keep track of elements whose next greater element is not yet found

• If the current element is greater than the top element of the stack, pop the stack and mark the popped element's next greater element as the current element

• Push the current element onto the stack

• If there ar...read more
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Q2. Question based on Sql inner join
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Q1. Tell about yourself
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Q2. Past experience
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Q3. Last ctc salary
Ans. 
Discussing last CTC salary helps gauge expectations and market alignment for the Team Lead role.
• CTC stands for Cost to Company, which includes all benefits and allowances.

• For example, if my last CTC was $80,000, it included base salary, bonuses, and health benefits.

• It's important to consider the entire compensation package, not just the base salary.

• I believe in transparency regarding salary discussions to ensure mutual...read more
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Q1. DSA Round & Introduction Round
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Q2. DP Question related to subsequence
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Q1. Design Parking Lot
Ans. 
Design a parking lot system with multiple levels and spots for cars.
• Create a class for ParkingLot with attributes like levels, spots per level, etc.

• Implement methods for parking a car, removing a car, checking availability, etc.

• Consider implementing a ticketing system for tracking parked cars.

• Utilize data structures like arrays, lists, or maps to manage parking spots efficiently.
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Q2. Sort Numbers with large file
Ans. 
Use external sorting algorithm like merge sort to efficiently sort numbers in a large file.
• Break the large file into smaller chunks that can fit into memory

• Sort each chunk individually using a sorting algorithm like merge sort

• Merge the sorted chunks back together to get the final sorted result
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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