Tower Research Capital LLC Interview Questions and Answers

Round duration - 45 Minutes
Round difficulty - Easy

The interviewer was friendly. Explained the question well. Allowed to use any preferred platform to write code.

Q1. 
Best Time to Buy and Sell Stock Problem Statement
Given an array prices representing the prices of a stock where each element indicates the price at a given minute, determine the maximum profit you can ac...read more
Ans. 
Find the maximum profit by buying and selling a stock once based on given prices.
• Iterate through the prices array and keep track of the minimum price seen so far and the maximum profit achievable.

• Calculate the profit by subtracting the current price from the minimum price and update the maximum profit if needed.

• Return the maximum profit, ensuring it is not negative.

• Example: prices = [2, 100, 150, 120], Buy at 2, sell a
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Round duration - 60 Minutes
Round difficulty - Medium

Q1. 
Dance Team Pairing Challenge
Imagine you are helping Ninja, a dance coach, who needs to form dance pairs from the available boys and girls in a studio. Given the number of boys N, the number of girls M, a...read more
Ans. 
The challenge involves forming dance pairs from available boys and girls based on potential pairings to maximize the number of pairs.
• Parse the input to get the number of test cases, boys, girls, and potential pairings.

• Iterate through the potential pairings and form pairs based on the given indexes.

• Output '1' if a set of maximum possible pairs is returned, else output '0'.

• There can be multiple valid configurations of pa...read more
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Q2. What is the difference between multiprocessing and multithreading?
Ans. 
Multiprocessing involves multiple processes running concurrently, while multithreading involves multiple threads within a single process.
• Multiprocessing utilizes multiple processes to execute tasks simultaneously.

• Multithreading involves multiple threads within a single process sharing the same memory space.

• Multiprocessing is typically used for CPU-bound tasks, while multithreading is more suitable for I/O-bound tasks.

• E...read more
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Round duration - 60 Minutes
Round difficulty - Hard

Q1. Can you describe the classes and functions involved in the design of a system like Splitwise?
Ans. 
Splitwise is a system for managing shared expenses among groups of people.
• Classes: User, Expense, Group

• Functions: addExpense(), settleUp(), calculateBalance()
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Round duration - 60 Minutes
Round difficulty - Hard

Round duration - 90 minutes
Round difficulty - Easy

Consisted of 3 DSA questions and MCQ on python proficiency

Q1. 
Palindromic Substrings Problem Statement
Given a string S, your task is to return all distinct palindromic substrings of the given string in alphabetical order.
Explanation:
A string is considered a pal...read more
Ans. 
Return all distinct palindromic substrings of a given string in alphabetical order.
• Iterate through all possible substrings of the given string.

• Check if each substring is a palindrome by comparing it with its reverse.

• Store all palindromic substrings in a set to ensure uniqueness.

• Return the sorted list of palindromic substrings.
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Round duration - 60 minutes
Round difficulty - Medium

It was a pure DSA round and interviewer was very helpful with providing significant hints to solve the given problems

Q1. 
Island Perimeter Calculation Problem
Given a binary grid representation of a map of an island, calculate the perimeter of the island. The grid uses '0' for water and '1' for land.
The grid has only one i...read more
Ans. 
Calculate the perimeter of an island represented by a binary grid.
• Iterate through the grid and count the perimeter based on land cells and their adjacent cells.

• Each land cell contributes 4 units to the perimeter, subtract 2 units for each adjacent land cell.

• Handle edge cases where land cells are at the boundaries of the grid.

• Return the total perimeter for each test case.
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Round duration - 60 minutes
Round difficulty - Hard

DSA+OS

Q1. 
Clearing the Forest Problem Statement
Ninja lives in a city called Byteland where a festive event is being organized. To make space for this event, Ninja is tasked with clearing a nearby forest. The fores...read more
Ans. 
Calculate the minimum number of steps Ninja needs to cut down all trees in a forest grid.
• Iterate through the grid to find the shortest path to cut down all trees in order.

• Use a priority queue to keep track of the shortest trees to cut next.

• If it's impossible to cut all trees, return -1.

• Consider all four cardinal directions for movement in the grid.
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Q1. Introductory questions
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Q2. All security concepts
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Q3. Practical scenarios and explanations
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Q1. Details practical test
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Q2. Explaining incidents faced
Ans. 
I have faced incidents related to system crashes, network failures, and security breaches.
• System crash due to hardware failure

• Network failure due to misconfiguration

• Security breach due to weak password policy

• DDoS attack causing website downtime
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Q3. Counter questions and reason for selecting the approach
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Q1. Explaining the role suitability and reason for change
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Q1. Why are you looking for a change?
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Q2. What is your family background?
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Q3. Share details of your previous job.
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Q4. What are your salary expectations?
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Q5. Why should we hire you?
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Q6. What are your strengths and weaknesses?
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Q7. Tell me about yourself.
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Round duration - 90 minutes
Round difficulty - Medium

Q1. 
Word Ladder Problem Statement
Given two strings, BEGIN and END, along with an array of strings DICT, determine the length of the shortest transformation sequence from BEGIN to END. Each transformation inv...read more
Ans. 
The Word Ladder problem involves finding the shortest transformation sequence from one word to another by changing one letter at a time.
• Use breadth-first search to find the shortest transformation sequence.

• Create a graph where each word is a node and edges connect words that differ by one letter.

• Keep track of visited words to avoid revisiting them.

• Return -1 if no transformation sequence is possible.
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Round duration - 50 minutes
Round difficulty - Medium

Q1. 
Number of Islands Problem Statement
You are provided with a 2-dimensional matrix having N rows and M columns, containing only 1s (land) and 0s (water). Your goal is to determine the number of islands in t...read more
Ans. 
Count the number of islands in a 2D matrix of 1s and 0s.
• Use Depth First Search (DFS) or Breadth First Search (BFS) to traverse the matrix and identify connected groups of 1s.

• Maintain a visited array to keep track of visited cells to avoid redundant traversal.

• Increment the island count whenever a new island is encountered.

• Consider all eight possible directions for connectivity between cells.

• Handle edge cases like out of
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Round duration - 50 minutes
Round difficulty - Medium

Q1. 
Rotting Oranges Problem Statement
You are given a grid containing oranges where each cell of the grid can contain one of the three integer values:
• 0 - representing an empty cell
• 1 - representing a fre...read more
Ans. 
Find the minimum time required to rot all fresh oranges in a grid.
• Use Breadth First Search (BFS) to simulate the rotting process

• Track the time taken to rot all oranges and return it

• If any fresh oranges remain after simulation, return -1

• Handle edge cases like empty grid or no fresh oranges
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Round duration - 90 minutes
Round difficulty - Medium

Q1. How would you design a system like Splitwise?
Ans. 
Splitwise is a system for managing shared expenses among groups of people.
• 1. Allow users to create groups and add members to track shared expenses.

• 2. Implement features for adding expenses, specifying who paid and who owes.

• 3. Calculate balances for each member and settle debts efficiently.

• 4. Provide notifications and reminders for pending payments.

• 5. Ensure security and privacy of user data.

• 6. Implement features like e...read more
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Round duration - 90 minutes
Round difficulty - Medium

There were
1. 25 C++/Java/Shell based MCQs
2. 2 SQL based questions - you are expected to write sql query based on the problem statement
3. Create React App - Todo App

Deadline was 7 days

Q1. Given an employee table and a department table, how would you output the person with the maximum earnings from each department?
Ans. 
Output the person with the maximum earnings from each department
• Join the employee and department tables on department ID

• Group by department ID and find the max earnings for each department

• Join the result with the employee table to get the person with max earnings
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Round duration - 60 Minutes
Round difficulty - Hard

It was in afternoon 2PM. Interviewer was polite and helpful. He was trying me to push me more. At the end of the interview, he even gave me the good feedback

Q1. 
Minimum Cost to Reduce Array
Given an array ARR of size N containing positive integers, the task is to reduce the size of the array to 1 by performing a specific operation multiple times. In one operation...read more
Ans. 
Find the minimum cost to reduce an array to one element by merging adjacent elements.
• Iterate through the array and merge adjacent elements with the smallest sum each time.

• Keep track of the total cost as you merge elements.

• Repeat the merging process until only one element remains in the array.
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Round duration - 60 Minutes
Round difficulty - Medium

It was in the noon 2.30PM. Interviewer was the team lead. Interviewer was polite and helpful

Round duration - 30 Minutes
Round difficulty - Medium

Interviewer was the Division Manager. Was just scratching the surface in all domain like behavioural, tech questions, situational questions

Round duration - 60 minutes
Round difficulty - Easy

This was the qualification round which comprised of several MCQs and 3 coding questions.
It was held on Hackerearth from 3:00 PM to 4:00 PM.
Use of any other IDE was prohibited.

Q1. Given a problem statement and a piece of code, how would you find and correct the bug in the code?
Ans. 
To find and correct a bug in code, analyze problem statement, review code, use debugging tools, and test different scenarios.
• Understand the problem statement and expected output.

• Review the code for syntax errors, logical errors, and potential bugs.

• Use debugging tools like breakpoints, print statements, and IDE debuggers.

• Test the code with different inputs to identify the bug.

• Make necessary corrections based on the iden...read more
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Q2. 
Print Nodes at Distance K from a Given Node
Given an arbitrary binary tree, a node of the tree, and an integer 'K', find all nodes that are at a distance K from the specified node, and return a list of th...read more
Ans. 
Given a binary tree, a target node, and an integer K, find all nodes at distance K from the target node.
• Traverse the binary tree to find the target node.

• Use BFS to traverse the tree from the target node to nodes at distance K.

• Keep track of the distance while traversing the tree.

• Return the values of nodes at distance K in any order.
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Round duration - 90 minutes
Round difficulty - Medium

I was shared a link of Google Meet and the Google Docs was shared where there was 1 coding problem to be coded there and then the code was run on an IDE to check the sample tests.
Then the interview was followed by a lot of Operating System and Computer System Architecture Questions.
There were 2 Interviewers and both were helpful.
The timing was from 2:30 PM to 4:00 PM

Q1. 
Subarray Challenge: Largest Equal 0s and 1s
Determine the length of the largest subarray within a given array of 0s and 1s, such that the subarray contains an equal number of 0s and 1s.
Input:
Input beg...read more
Ans. 
Find the length of the largest subarray with equal number of 0s and 1s in a given array.
• Iterate through the array and maintain a count of 0s and 1s encountered so far.

• Store the count difference in a hashmap with the index as the key.

• If the same count difference is encountered again, the subarray between the two indices has equal 0s and 1s.

• Return the length of the longest subarray found.
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Round duration - 45 minutes
Round difficulty - Easy

The round was held on Google Meet with HR from 2:30 PM to 3:15 PM.
The HR was friendly and asked the basic questions.