Freecharge SDE (Software Development Engineer) Interview Questions and Answers

Q1. It was an MCQ Round and the questions were a mixture of CS fundamentals topics.
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This round contained 2 coding questions.

Q1. This was a one on one coding round where I was asked 3 questions that were of Easy to Medium level of LeetCode.
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Q1. HR round was more of a technical interview round where I was asked about my android projects and some core android topics since both me and my interviewer were Android Developers.
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3 coding question 1 SQL query

Q1. Question about tree check tree is bst or not ?write code on it
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Q2. Array question find 1st repeated element in o(n).
Ans. 
Find the first repeated element in an array of strings in O(n) time complexity.
• Create a hash table to store the frequency of each element.

• Traverse the array and check if the element is already present in the hash table.

• If it is present, return the element as the first repeated element.

• If no element is repeated, return null or -1.

• Example: ['apple', 'banana', 'orange', 'apple'] => 'apple'
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Q1. Multiple of big integers and find complexity
Ans. 
Question about finding complexity of multiplying big integers.
• Big integers require more memory and processing power than regular integers.

• Multiplying two n-digit integers takes O(n^2) time using the standard algorithm.

• There are faster algorithms like Karatsuba and FFT which have lower complexity.

• The complexity of multiplying two n-digit integers using Karatsuba algorithm is O(n^log2(3)).

• The complexity of multiplying tw...read more
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Q1. Where do you see yourself in 5 years?
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Q2. What are your strengths and weaknesses?
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Q3. Tell me about yourself.
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15 MCQs and 2 coding questions were given. MCQs include questions from topics like dbms, system design, oops etc.
1st coding question was of dp and 2nd was of a good question of graph.

Q1. Create a linked list from scratch and then delete a given node. Then print the linked list.
Ans. 
Create and delete a node in a linked list and print the updated list.
• Create a Node class with data and next pointer attributes

• Create a LinkedList class with head attribute and methods to add, delete and print nodes

• To delete a node, traverse the list and update the next pointer of the previous node to skip the node to be deleted

• Print the list by traversing and printing the data of each node
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Q2. Reverse first K(given) characters of string.
Ans. 
Reverse the first K characters of a given string.
• Take the first K characters of the string.

• Reverse the selected substring.

• Concatenate the reversed substring with the rest of the original string.
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Round duration - 90 minutes
Round difficulty - Easy

Nice environment

Q1. 
Zigzag Traversal of Binary Tree
Given a binary tree with integer values in its nodes, your task is to print the zigzag traversal of the tree.
Note:
In zigzag order, level 1 is printed from left to right...read more
Ans. 
Implement a function to print the zigzag traversal of a binary tree.
• Traverse the tree level by level, alternating the direction of traversal for each level.

• Use a queue to keep track of nodes at each level.

• Print the nodes in zigzag order as per the given pattern.
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Round duration - 90 minutes
Round difficulty - Medium

Nice Environment

Q1. 
Prime Numbers Identification
Given a positive integer N, your task is to identify all prime numbers less than or equal to N.
Explanation:
A prime number is a natural number greater than 1 that has no po...read more
Ans. 
Identify all prime numbers less than or equal to a given positive integer N.
• Iterate from 2 to N and check if each number is prime

• Use the Sieve of Eratosthenes algorithm for better efficiency

• Optimize by only checking up to the square root of N for divisors
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Q2. What was the use of DBMS in your project, and how did you handle the problems that arose?
Ans. 
DBMS was used to store and manage data in the project, handled problems by optimizing queries and database design.
• Used DBMS to store and manage project data efficiently

• Optimized queries for better performance

• Designed database schema to handle data effectively

• Resolved concurrency issues by implementing proper locking mechanisms
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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.

Round duration - 90 minutes
Round difficulty - Medium

Timing was 9 PM. Platform was not good. Platform was very lagging so overall it was bad experience.

Q1. 
Find the Third Greatest Element
Given an array 'ARR' of 'N' distinct integers, determine the third largest element in the array.
Input:
The first line contains a single integer 'T' representing the numb...read more
Ans. 
Find the third largest element in an array of distinct integers.
• Sort the array in descending order and return the element at index 2.

• Handle cases where the array has less than 3 elements separately.

• Use a set to store distinct elements for efficient processing.
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Q2. 
Longest Palindromic Substring Problem Statement
You are provided with a string STR of length N. The task is to find the longest palindromic substring within STR. If there are several palindromic substring...read more
Ans. 
Find the longest palindromic substring in a given string.
• Iterate through the string and expand around each character to find palindromes

• Keep track of the longest palindrome found so far

• Return the longest palindromic substring
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Q3. 
Ninja and Geometry Problem Statement
In this problem, Ninja is provided with two lines on a 2D plane. The first line 'AB' is determined by two points A and B. The second line 'PQ' is determined by two poi...read more
Ans. 
Calculate the intersection point of two lines on a 2D plane with precision up to six decimal places.
• Implement a function to calculate the intersection point of two lines on a 2D plane

• Handle precision up to six decimal places in the output

• Return -1.000000 -1.000000 if the lines do not intersect

• Ensure the lines 'AB' and 'PQ' are distinct
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Round duration - 90 minutes
Round difficulty - Medium

Timing was 9 PM. Platform was not good. Platform was very lagging so overall it was bad experience.

Q1. 
Find the Third Greatest Element
Given an array 'ARR' of 'N' distinct integers, determine the third largest element in the array.
Input:
The first line contains a single integer 'T' representing the numb...read more
Ans. 
Find the third largest element in an array of distinct integers.
• Sort the array in descending order and return the element at index 2.

• Handle cases where there are less than 3 elements in the array.

• Consider edge cases like negative integers and duplicates.
Answered by AI
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Q2. 
Longest Palindromic Substring Problem Statement
You are provided with a string STR of length N. The goal is to identify the longest palindromic substring within this string. In cases where multiple palind...read more
Ans. 
Identify the longest palindromic substring in a given string.
• Iterate through each character in the string and expand around it to find palindromes

• Keep track of the longest palindrome found so far

• Return the longest palindromic substring with the smallest start index
Answered by AI
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Q3. 
Ninja and Geometry Problem Statement
In this problem, Ninja is provided with two lines on a 2D plane. The first line 'AB' is determined by two points A and B. The second line 'PQ' is determined by two poi...read more
Ans. 
Calculate the intersection point of two lines on a 2D plane with precision up to six decimal places.
• Implement a function to calculate the intersection point of two lines on a 2D plane

• Handle precision up to six decimal places in the output

• Return -1.000000 -1.000000 if the lines do not intersect

• Ensure the lines 'AB' and 'PQ' are distinct
Answered by AI
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