Upstox Software Developer Intern Interview Questions and Answers

There were DSA questions and time limit was 1 hr

Q1. Calculate factorial using tabulation
Ans. 
Factorial calculation using tabulation in dynamic programming
• Create an array to store factorial values up to n

• Initialize the array with base cases (0! = 1, 1! = 1)

• Iterate from 2 to n and calculate factorial using previous values in the array

• Return the factorial value at index n
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Q2. Wildcard matching question
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Creating a Web App using React JS and Java Servlets

4 coding problems + 1 sql problem

Q1. Gas Station Problem On leetcode
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Q2. Simple Tree Traversal Problem LC medium
Ans. 
Given a binary tree, return the inorder traversal of its nodes' values.
• Inorder traversal: left subtree, root, right subtree

• Use recursion to traverse the tree

• Implement a stack-based iterative solution for better space complexity
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Q1. There were basic DSA questions
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Q2. Few questions based on Resume and Projects
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Round duration - 90 minutes
Round difficulty - Easy

The online round had 2 coding questions and one question of a regular expression.

Q1. 
Find All Pairs Adding Up to Target
Given an array of integers ARR of length N and an integer Target, your task is to return all pairs of elements such that they add up to the Target.
Input:
The first line ...read more
Ans. Hashing Solution
• We can store the frequency of every element in the array in a hashmap.
• We will loop over every index i, and check the frequency of (Target - ARR[i]) is the hashmap:
  • If (Target - ARR[i]) is equal to ARR[i], we will check if frequency of ARR[i] . If it is greater than 1 then we will decrease the frequency of ARR[i] by 2 and add a pair (ARR[i] , ARR[i]) to our answer.
  • Else, if the frequency of ARR[i] and Targ...read more
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Q2. 
Increasing Subsegment Problem Statement
Given a sequence ARR consisting of N integers, your task is to identify the longest subsegment of ARR, where you can change at most one number to make the subsegmen...read more
Ans. Dynamic Programming
Here, the idea is to calculate the longest increasing subarray for every element by taking it as the starting as well as the ending point.
 
Here is the algorithm:
 
1. We first compute the longest increasing subarray ending at an index for every index in the given array. We store these values in l[].
2. Then calculate the longest increasing subarray starting at an index for every index in the given a...read more
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Round duration - 60 minutes
Round difficulty - Easy

First 10 minutes started with the Introduction. Then he asked about my projects. He seemed interested in my projects and asked a lot of questions about them. He asked questions related to Node Js, React Js, Mongo DB, AWS as all these were mentioned in my Resume. Around 25 minutes was completed explaining each and everything.

Then he started with the coding questions. I was allowed to share my screen and use any of my favourite text editors. I chose ‘VS Code’.

I was able to solve 2 coding questions very easily. I got stuck in the puzzle as I didn’t solve any puzzles before. I was able to come up with different approaches, but they weren’t the most optimal. He tried giving me a lot of hints but still wasn’t able to solve it. I had a positive can-do attitude throughout, and I was really close to solving it.

Feedback: He told me I performed well and asked if I had any questions for him. I asked for the solution to the puzzle. He explained to me the solution and I told him that I will practice puzzles.

Around 5-6 students got selected for 2nd Interview.

Q1. 
Move Zeros To Left
You are provided an array ARR of integers. Your task is to rearrange this array such that all elements with zero values are moved to the left, and all non-zero elements follow them, pre...read more
Ans. Solution Using Extra space
The idea is to use an extra vector to store all the non-zero elements while maintaining their relative order. So we will first add all the non-zero elements to a vector and then iterate that vector backwards and start updating the array values from end. In the end we will set all the array values whose values were not updated to 0. 
Steps:
1. Let storeNonZero be the vector that stores non-zero...read more
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Q2. 
Maximum Sum of Disjoint Pairs with Specific Difference
Given an array of integers and a number K, your task is to form pairs of elements from the array such that the absolute difference between them is st...read more
Ans. Sorting
Approach: We sort the given array in increasing order. For every element, we try to pair it with its previous element first. Since the array is sorted, the value of ‘ARR[i]’ would be more than ‘ARR[i - 1]’. We need to pair with a difference less than ‘K’, which means if 'ARR[i - 2]' can be paired, then ‘ARR[i - 1]’ can also be paired in a sorted array. Here, we prefer the previous element so that if ‘ARR[i]’ - ‘...read more
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Round duration - 35 minutes
Round difficulty - Medium

It started with a brief Introduction and in-depth discussions on projects. He also asked me a lot of questions about my previous internship. He asked me some behavioural questions as well.

I was able to solve the question, and he did not ask me any other questions. This round was really short for me and was finished in around 35 minutes, well before time. I asked about my feedback, and he told me that the ‘HR’ will get back to me. I thought he was not satisfied with my answers and I will be rejected though I gave very good answers to every question.

3 students got selected for the next round. I think he was satisfied and did not want to waste more time asking questions.

Q1. 
Polynomial Simplification Problem Statement
You are provided with two arrays representing the coefficients and degrees of a polynomial expression. Your task is to simplify this polynomial into its general...read more
Ans. Using a map to store coefficients
1. Initialise a map which will store the coefficients as value and exponent as key.
2. For every term in the polynomial, update the coefficients in the map.
3. If the coefficient becomes zero then remove the entry from the map.
4. Sort the key values in descending order.
5. Initialize the answer array.
6. Add all non-zero coefficients in the array and return it.
Space Complexity: OtherExplanation:
O(K), where ...read more
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Round duration - 60 minutes
Round difficulty - Medium

It started with an introduction and discussion on projects. He seemed very curious about my project and went ahead to cross-question every functionality. We discussed everything and how the code works. He asked me a lot of questions on ‘Socket’ as my project mentioned it.

HR-related questions such as:
Why do you want to join the company?
Where do you see yourself in the next 5 years?
What are your strengths and weakness?

They first taught React ,javaEE and sql and than told us to make a full stack B2b invoice management system