Infinx Technical Architect Interview Questions and Answers

Round duration - 90 minutes
Round difficulty - Medium

Q1. 
Longest Increasing Subsequence Problem Statement
Given 'N' students standing in a row with specific heights, your task is to find the length of the longest strictly increasing subsequence of their heights...read more
Ans. 
Find the length of the longest strictly increasing subsequence of heights of students in a row.
• Iterate through the heights array and for each element, find the length of the longest increasing subsequence ending at that element.

• Use dynamic programming to keep track of the longest increasing subsequence length for each element.

• Return the maximum length found as the result.
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Q2. 
Overlapping Intervals Problem Statement
You are given the start and end times of 'N' intervals. Write a function to determine if any two intervals overlap.
Note:
If an interval ends at time T and anothe...read more
Ans. 
Given start and end times of intervals, determine if any two intervals overlap.
• Iterate through intervals and check if any two intervals overlap by comparing their start and end times

• Sort intervals based on start times for efficient comparison

• Consider edge cases where intervals end and start at the same time
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Q3. What SQL queries were asked during your interview?
Ans. 
Various SQL queries related to data manipulation and retrieval were asked during the interview.
• Basic SELECT queries to retrieve data from a single table

• JOIN queries to retrieve data from multiple tables based on a common column

• Aggregate functions like COUNT, SUM, AVG, etc. to perform calculations on data

• Subqueries to retrieve data based on the result of another query

• UPDATE queries to modify existing data in a table

• DELE...read more
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Round duration - 60 Minutes
Round difficulty - Medium

Q1. 
Zig-Zag String Problem Statement
Given a string STR of size N and an integer M representing the number of rows in the zig-zag pattern, return the string formed by concatenating all rows when the string ST...read more
Ans. 
Arrange a string in zig-zag pattern with given number of rows and concatenate the rows.
• Iterate through the string and distribute characters to rows based on zig-zag pattern

• Concatenate the characters in each row to get the final result

• Handle edge cases like when number of rows is 1 or equal to the length of the string
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Q2. 
Next Permutation Problem Statement
You are given a permutation of 'N' integers. A sequence of 'N' integers is considered a permutation if it includes all integers from 1 to 'N' exactly once. Your task is ...read more
Ans. 
The task is to rearrange a given permutation of 'N' integers to form the lexicographically next greater permutation.
• Iterate from right to left to find the first element that is smaller than the element to its right.

• Swap this element with the smallest element to its right that is greater than it.

• Reverse the elements to the right of the swapped element to get the lexicographically next greater permutation.
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Round duration - 60 Minutes
Round difficulty - Medium

Q1. 
Remove Consecutive Duplicates Problem Statement
Given a string S, your task is to recursively remove all consecutive duplicate characters from the string.
Input:
String S
Output:
Output string
Constr...read more
Ans. 
Recursively remove consecutive duplicate characters from a string.
• Use recursion to check if the current character is the same as the next character, if so skip the next character

• Base case: if the string is empty or has only one character, return the string

• Example: Input: 'aaabcc', Output: 'abc'
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Q2. 
Print Permutations - String Problem Statement
Given an input string 'S', you are tasked with finding and returning all possible permutations of the input string.
Input:
The first and only line of input ...read more
Ans. 
Return all possible permutations of a given input string.
• Use recursion to generate all possible permutations of the input string.

• Swap characters at different positions to generate permutations.

• Handle duplicate characters in the input string by using a set to store unique permutations.
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Round duration - 60 Minutes
Round difficulty - Medium

Q1. Design an e-commerce website similar to Flipkart or Amazon.
Ans. 
Design an e-commerce website similar to Flipkart or Amazon.
• Implement user-friendly interface for easy navigation

• Include search functionality with filters for products

• Incorporate secure payment gateway for transactions

• Provide personalized recommendations based on user behavior

• Include customer reviews and ratings for products

• Implement order tracking and delivery status updates

• Offer various payment options like credit/deb
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Round duration - 90 minutes
Round difficulty - Medium

This round was conducted in Hackerrank portal for a total duration of 95 minutes and was divided into 4 sections.

1st Section : Aptitude Section : 14 questions , 28 minutes
2nd Section : Technical Section : 12 questions , 17 minutes
3rd Section :1 coding Questions : 20 minutes+30 minutes

Q1. 
Water Equalization Problem Statement
You are provided with an array ARR of positive integers. Each integer represents the number of liters of water in a bucket. The goal is to make the liters of water in ...read more
Ans. 
Given an array of water buckets, find the minimum liters of water to remove to make all buckets contain the same amount of water.
• Iterate through the array to find the most common amount of water in the buckets.

• Calculate the total liters of water that need to be removed to equalize all buckets to the most common amount.

• Return the total liters of water to be removed.
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Q2. 
Rat in a Maze Problem Statement
You need to determine all possible paths for a rat starting at position (0, 0) in a square maze to reach its destination at (N-1, N-1). The maze is represented as an N*N ma...read more
Ans. 
Find all possible paths for a rat in a maze from source to destination.
• Use backtracking to explore all possible paths in the maze.

• Keep track of visited cells to avoid revisiting them.

• Explore all possible directions (up, down, left, right) from each cell.

• Add the current direction to the path and recursively explore further.

• If the destination is reached, add the path to the list of valid paths.
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Round duration - 120 Minutes
Round difficulty - Medium

This was an Online F2F Technical Round conducted on CodePair : Hackerrank. So, Basically You have to Run and Submit ( Pass All Test cases) in the Interview Round also (Like normal Coding Test) in Codepair : Hackerrank & along with that You should have to explain your Code and Approach to the Interviewers.
The Interviewers were helpful and didn't hesitate in giving hints.
Timing - 10:00 A.M to 12:00 P.M

Q1. 
Minimum Fountains Activation Problem
In this problem, you have a one-dimensional garden of length 'N'. Each position from 0 to 'N' has a fountain that can provide water to the garden up to a certain range...read more
Ans. 
Find the minimum number of fountains to activate to water the entire garden.
• Iterate through the array to find the coverage of each fountain.

• Keep track of the farthest coverage reached by activating fountains.

• Activate the fountain that covers the farthest point not yet covered.

• Repeat until the entire garden is watered.
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Q2. 
Minimize Cash Flow Problem
You are provided with a list of 'transactions' involving 'n' friends who owe each other money. Each entry in the list contains information about a receiver, sender, and the tran...read more
Ans. 
Minimize cash flow problem among friends by optimizing transactions.
• Create a graph where nodes represent friends and edges represent transactions.

• Calculate net amount each friend owes or is owed by summing up all transactions.

• Use a recursive algorithm to minimize cash flow by settling debts between friends.

• Update the graph and repeat the process until all debts are settled.
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Round duration - 120 Minutes
Round difficulty - Hard

A lot of Variants based on Constraints were asked in this Round. They will ask you to write the final code for every question before Submitting it(run all test cases) so you won’t get any hints after running test cases in the IDE. ( So don’t Submit your code before dry running it on a lot of Test Cases on pen & paper , they allow to use pen & blank paper at the time of Interviews) .The Interviewers tried to trick in case of time complexities even if you gave the best one. So try to be confident.

Q1. 
Buy and Sell Stock Problem Statement
Imagine you are Harshad Mehta's friend, and you have been given the stock prices of a particular company for the next 'N' days. You can perform up to two buy-and-sell ...read more
Ans. 
The task is to determine the maximum profit that can be achieved by performing up to two buy-and-sell transactions on a given set of stock prices.
• Iterate through the array of stock prices and keep track of the maximum profit that can be achieved by buying and selling at different points.

• Maintain variables to store the maximum profit after the first transaction, the maximum profit after the second transaction, and the m...read more
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Round duration - 30 minutes
Round difficulty - Easy

This was HR Round. The HR was friendly and asked basic questions.
The timing was 2:00 PM to 2:30 PM.

Round duration - 75 minutes
Round difficulty - Easy

This was the coding round which consisted of three coding questions and the time limit was of 75 minutes. The platform used was Co-Cubes. 3 questions were asked of 2, 3 and 5 marks respectively with varying difficulty.

Q1. 
Nearest Multiple of 10 Problem Statement
Given an integer N, find the nearest multiple of 10. If there are multiple nearest multiples, return the smallest one.
Input:
The first line contains an integer ...read more
Ans. 
Given an integer, find the nearest multiple of 10. If multiple nearest multiples, return the smallest one.
• Iterate through each test case

• Calculate the remainder when dividing N by 10

• If remainder is less than or equal to 5, nearest multiple is N - remainder

• If remainder is greater than 5, nearest multiple is N + (10 - remainder)
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Q2. 
Day of the Week Calculation
Your task is to create a function that determines the day of the week for any given date, whether in the past or the future.
Input:
The first line consists of an integer 'T',...read more
Ans. 
Create a function to determine the day of the week for any given date.
• Parse the input integers to create a date object

• Use a library or algorithm to calculate the day of the week for the given date

• Return the corresponding day of the week as a string
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Q3. 
Delete N Nodes After M Nodes in a Linked List
Given a singly linked list and two integers 'N' and 'M', traverse the linked list to retain 'M' nodes and then delete the next 'N' nodes. Continue this proces...read more
Ans. 
Traverse a linked list to retain 'M' nodes and then delete the next 'N' nodes, repeating until the end of the list.
• Create a function that takes the head of the linked list, 'N', and 'M' as input parameters.

• Traverse the linked list, retaining 'M' nodes and deleting the next 'N' nodes in each iteration.

• Continue this process until the end of the linked list is reached.

• Update the next pointers accordingly to skip 'N' nodes...read more
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Round duration - 30 minutes
Round difficulty - Easy

This was a written round and we were expected to write fully functional code, without any bugs and errors. Library functions used if any, had to be explained and if possible, code for that too (not that rigorous). Pseudocode and algorithms were also allowed. All the assumptions made had to be explained as well.

Q1. 
Look-And-Say Sequence Problem Statement
The Look-And-Say sequence is a series of positive integers generated in a specific pattern:
1, 11, 21, 1211, 111221, 312211, 13112221,...
To construct this sequen...read more
Ans. 
The Look-And-Say sequence is a series of positive integers generated in a specific pattern based on the count of digits in the previous number.
• Implement a function to generate the Nth term of the Look-And-Say sequence efficiently.

• Use a loop to iterate through the sequence generation process.

• Keep track of the count of consecutive digits in each number to generate the next number.

• Handle the constraints of the number of t...read more
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Q2. 
Rearrange Array to Form Largest Number
Given an array ARR consisting of non-negative integers, rearrange the numbers to form the largest possible number. The digits within each number cannot be changed.
...read more
Ans. 
Rearrange the array elements to form the largest possible number by concatenating them.
• Sort the array elements in a custom way to form the largest number.

• Convert integers to strings for comparison while sorting.

• Handle edge cases like leading zeros in the final number.

• Example: For input [12, 5, 34], the output should be '53412'.
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Round duration - 50 minutes
Round difficulty - Easy

The interviewer was very friendly and started asking me questions by making me comfortable.

Q1. 
Simplify Directory Path Problem Statement
You are provided with a directory path in Unix-style notation, and your task is to simplify it according to given rules.
In a Unix-style file system:
• A dot (...read more
Ans. 
The task is to simplify a directory path in Unix-style notation according to given rules.
• Use a stack to keep track of directories while iterating through the input path.

• Handle cases for '.', '..', and multiple slashes to simplify the path.

• Return the simplified path starting with a slash and without a trailing slash.
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Q2. 
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. 
Simplify a polynomial expression by combining like terms and arranging them in descending order of degrees.
• Iterate through the coefficients and degrees arrays to combine like terms

• Create a map to store coefficients based on degrees

• Sort the map keys in descending order to get the simplified polynomial
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Round duration - 40 minutes
Round difficulty - Easy

This round was focused on resume and projects

Round duration - 30 minutes
Round difficulty - Easy

This round was basically a mix of HR and creative design round. The interviewer wanted to check whether the candidate can think out-of-the-box with regard to any given problem and come up with unique, optimized solutions.