Helpshift Software Developer Interview Questions and Answers

Round duration - 45 minutes
Round difficulty - Medium

This was a technical round.

Q1. Find duplicate in array
You are given an array/list 'ARR' consisting of N integers, which contains elements only in the range 0 to N - 1. Some of the elements may be repeated in 'ARR'. Your...read more
Ans. 
Concept of indexing can be used to solve this question.
Traverse the array. For every element at index i,visit a[i]. If a[i] is positive, then change it to negative. If a[i] is negative, it means the element has already been visited and thus it is repeated. Print that element.
Pseudocode :
findRepeating(arr[], n)
{
	missingElement = 0
	for (i = 0; i < n; i++){
		element = arr[abs(arr[i])]

		if(element < 0){
...read more
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Q2. Find a triplet that sum to a given value
You are given an array/list ARR consisting of N integers. Your task is to find all the distinct triplets present in the array which adds up to a given number K.
A...read more
Ans. 
Sorting can be used to solve this problem. Next, two -pointer technique can be applied on the sorted array.
Traverse the array and fix the first element of the triplet. Now use the Two Pointer technique to find if there is a pair whose sum is equal to x – array[i].
• Algorithm : 
1. Sort the given array.
2. Loop over the array and fix the first element of the possible triplet, arr[i].
3. Then fix two pointers, one at i...read more
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Round duration - 45 minutes
Round difficulty - Medium

This was a technical interview round with questions on Programming and algorithms.

Q1. Box Stacking
You are given a set of ‘n’ types of rectangular 3-D boxes. The height, width, and length of each type of box are given by arrays, ‘height’, ‘width’, and ‘length’ respectively, each consisting ...read more
Ans. 
• Make an integer matrix ‘boxes’ of dimension (3*n, 3), we will store all three rotations of each type of boxes in it.
• Generate all 3 rotations for all ‘n’ types of boxes, for simplicity we will consider ‘width’ always smaller than or equal to ‘length’. Store them in matrix ‘boxes’ such that ‘boxes[i][0]’, ‘boxes[i][1]’, ‘boxes[i][2]’ give height, width, length of ‘i’th box respectively.
• Sort the matrix ‘boxes’ in decreasi...read more
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Q2. Maximum Sum Subarray
Given an array of numbers, find the maximum sum of any contiguous subarray of the array.
For example, given the array [34, -50, 42, 14, -5, 86], the maximum sum would be 137, since w...read more
Ans. 
The direct approach to solve this problem is to run two for loops and for every subarray check if it is the maximum sum possible. 
Time complexity: O(N^2), Where N is the size of the array.
Space complexity: O(1)
The efficient approach is to use Kadane's algorithm. It calculates the maximum sum subarray ending at a particular index by using the maximum sum subarray ending at the previous position. 
Steps : 
D...read more
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Round duration - 50 minutes
Round difficulty - Medium

This was a difficult on to face as we have to hold phone and concentrate and explaining is also very difficult.

Q1. Stock Buy and sell
You are given an array/list 'prices' where the elements of the array represent the prices of the stock as they were yesterday and indices of the array represent minutes. Your tas...read more
Ans. 
The idea is to traverse the given list of prices and find a local minimum of every increasing sequence. We can gain maximum profit if we buy the shares at the starting of every increasing sequence (local minimum) and sell them at the end of the increasing sequence (local maximum). 
Steps :
1. Find the local minima and store it as starting index. If not exists, return.
2. Find the local maxima. and store it as an endi...read more
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Q2. Dijikstra Algorithm
You have been given an undirected graph of ‘V’ vertices (labeled 0,1,..., V-1) and ‘E’ edges. Each edge connecting two nodes (‘X’,’Y’) will have a weight denoting the distance between n...read more
Ans. 
Dijkstra's Algorithm basically starts at the source node and it analyzes the graph to find the shortest path between that node and all the other nodes in the graph.
The algorithm keeps track of the currently known shortest distance from each node to the source node and it updates these values if it finds a shorter path.
Once the shortest path between the source node and another node is found, that node is marked as "visi...read more
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Round duration - 30 minutes
Round difficulty - Easy

This was a small interaction just to make us familiar in Mumbai office.

Q1. Basic HR Questions
1. Introduce Yourself.
2. What do you think about Directi?
3. What are your favourite subjects?
4. Which programming language do you prefer?
Ans. 
Tip 1 : The cross questioning can go intense some time, think before you speak.

Tip 2 : Be open minded and answer whatever you are thinking, in these rounds I feel it is important to have opinion.

Tip 3 : Context of questions can be switched, pay attention to the details. It is okay to ask questions in these round, like what are the projects currently the company is investing, which team you are mentoring. How all is the
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Round duration - 90 minutes
Round difficulty - Medium

It consists of 3 questions:

The first question was related to DP (Hard)
Second was related to math(Easy)

Third was related to string (Medium)

Q1. Chocolate Pickup
Ninja has a 'GRID' of size 'R' X 'C'. Each cell of the grid contains some chocolates. Ninja has two friends Alice and Bob, and he wants to collect as many chocolate...read more
Ans. 
I was able to pass only 1 test case out of 5
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Q2. Trailing Zeros in Factorial
You are given an integer N, you need to find the number of trailing zeroes in N! (N factorial).
Note:
1. Trailing zeros in a number can be defined as the number of continuous...read more
Ans. 
I was able to pass only 3 test case out of 5
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Q3. Find K’th Character of Decrypted String
You have been given an Encrypted String where repetitions of substrings are represented as substring followed by the count of substrings.
Example: String "aabb...read more
Ans. 
I was able to pass all test cases
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Round duration - 45 minutes
Round difficulty - Medium

Standard DS/Algo round. It was at around 12 PM

Q1. Leaders in an array
Given a sequence of numbers. Find all leaders in sequence. An element is a leader if it is strictly greater than all the elements on its right side.
Note:
1. Rightmost element is alwa...read more
Ans. 
Start the iteration from the right side and keep the track of the maximum array till that particular element of the array.
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Q2. Find Two Missing Numbers
You are given an array of unique integers where each element in the array is in the range [1, N]. The array has all distinct elements, and the array’s size is (N - 2). Hence, two n...read more
Ans. 
First I solved this question in O(n) space and O(n) time then they asked me to optimize it and solve it without extra space.
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Q3. Reverse the Linked List
Given a singly linked list of integers. Your task is to return the head of the reversed linked list.
For example:
The given linked list is 1 -> 2 -> 3 -> 4-> NULL. The...read more
Ans. Brute Force
The brute force approach is to use recursion. First, we reach the end of the Linked List recursively and at last node, we return the last node, which becomes the new head of the partially reversed Linked List. While coming back from each recursion call we add the current node in the current recursion call to the last node of the partially reversed Linked List and assign the current node to null.
 
Steps:
&...read more
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Round duration - 35 minutes
Round difficulty - Easy

First, he asked me to introduce myself.
Then, he told me that as you know this is a design round so design a music player like Spotify. 
First, I have designed the database using tables and Primary and Foreign Keys.
Then, he told me to write the code for it and told me that before I write the code tell me that which data structure will you use and why?
Then, he discussed with me for around 10 to 15 min that why am I using particular DS and why not someone else and what will be the problem in a particular data structure, and how will certain DS perform in case of various operations like searching, adding, deleting the songs in the music player.
Then, he told me to write the code for a playlist of this music player with all possible operations.

Q1. System Design Question
Design a music player like Spotify
Ans. 
Tip 1 : First design the database and show them the database schema
Tip 2 : Then share your approach and data structures which you'll use
 
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Round duration - 30 minutes
Round difficulty - Easy

Interviewer was very friendly
And, timing was around 12.30 PM

Q1. Basic HR Question
Why should we hire you?
Ans. 
Tip 1 : The cross-questioning can go intense sometimes, think before you speak.

Tip 2 : Be open-minded and answer whatever you are thinking, in these rounds, I feel it is important to have an opinion.
 
Tip 3 : Context of questions can be switched, pay attention to the details. It is okay to ask questions in these rounds, like what are the projects currently the company is investing in, which team you are mentoring, ...read more
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Q2. Basic HR Question
Do you know anything about the company?
Ans. 
General Tip : Before an interview for any company, have a brief insight about the company, what it does, when was it founded and so on. All these info can be easily acquired from the Company Website itself.
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Round duration - 50 minutes
Round difficulty - Medium

A flexible window of 6 hours was provided to attempt the 1 hour test

Q1. Number Of Vehicles
There is a person named Bob who is the mayor of a state. He wants to find the maximise number of vehicles that can be registered in his state.
A vehicle normally has a registration num...read more
Ans. Permutation and Combinations
1. We can make use of basic Permutation and combination, to find out how many distinct vehicle registration numbers are possible.
2. Consider that we have 4 locations to fill with some digits and each location can acquire some digit from 0 to 9. Then the total possible ways to fill all locations in unique ways will be 10 X 10 X 10 X 10, as each location can acquire 10 different types of digits. In ...read more
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Q2. Find Palindromes
You are given an integer ‘N’. Your task is to find all palindromic numbers from 1 to ‘N’.
Palindromic integers are those integers that read the same backward or forwards.
Note:
Order o...read more
Ans. Brute Force
In this approach, iterate through the integers 1 to N, then check for each integer if it is a palindrome or not.
To check if an integer is a palindrome, convert the integer into a string and check if it is equal to the reverse.
We define a function isPalindrome(num), where we check if num is palindrome or not and return the result accordingly.
 
Algorithm:
• The function isPalindrome(num).
  • Convert the number nu...read more
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Round duration - 60 minutes
Round difficulty - Easy

The interviewer was chill and quite polite.

Q1. SQL Question
Write a query to output the data of students whose name starts with A
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Q2. Operating System Question
Define OS and Process table
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Q3. Find Duplicates In Array
You are given an array/list 'ARR' consisting of N integers, which contains elements only in the range 0 to N - 1. Some of the elements may be repeated in 'ARR'. You...read more
Ans. 
1. Input an ArrayList from the user
2. Traverse and store the occurence in hashmap 
3. Remove the elements with more than one frequency
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Round duration - 20 minutes
Round difficulty - Easy

Standard HR round with some behavioural questions

Q1. Basic HR Questions
1) Why should we hire you ?
2) What are your expectations from the company?
3) How was your overall interview experience?
4) What are your strengths and weakness according to you?
5) Where do...read more
Ans. 
Tip 1 : Focus on your positives
Tip 2 : Speak with confidence 
Tip 3 : Be honest
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Round duration - 60 minutes
Round difficulty - Medium

Students who qualified in first round gets link for this round, this round had 4 questions in total, out of which 1 was output based and 3 was DSA based.

Q1. Validate Binary Tree Nodes
You are given ‘N’ binary tree nodes numbered from 0 to N - 1 where node ‘i’ has two children LEFT_CHILD[i] and RIGHT_CODE[i]. Return ‘True’ if and only if all the given...read more
Ans. 
The task is to determine if the given binary tree nodes form exactly one valid binary tree.
• Check if there is only one root node (a node with no parent)

• Check if each node has at most one parent

• Check if there are no cycles in the tree

• Check if all nodes are connected and form a single tree
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Round duration - 75 minutes
Round difficulty - Medium

This round was of 70-75 minutes and had 3 coding questions of easy to medium level. There was some restrictions like we cannot use built-in functions in both second and third subjective round.

Q1. Balanced Binary Tree
You are given an integer 'H'. Your task is to count and print the maximum number of balanced binary trees possible with height 'H'.
The balanced binary tree is one in...read more
Ans. 
The maximum number of balanced binary trees possible with a given height is to be counted and printed.
• A balanced binary tree is one in which the difference between the left and right subtree heights is less than or equal to 1.

• The number of balanced binary trees can be calculated using dynamic programming.

• The number of balanced binary trees with height 'H' can be obtained by summing the product of the number of balanced...read more
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Round duration - 60 minutes
Round difficulty - Medium

This was face to face interview round of 60 minutes. It was mostly based on DSA, some questions was also asked related to my projects and DBMS. Interviewer was kind and good.

Q1. Sort an array in wave form
You have been given an unsorted array ‘ARR’.
Your task is to sort the array in such a way that the array looks like a wave array.
Example:
If the given sequence ‘ARR’ has ‘N’...read more
Ans. 
The task is to sort an array in a wave form, where each element is greater than or equal to its adjacent elements.
• Iterate through the array and swap adjacent elements if they do not follow the wave pattern

• Start from the second element and compare it with the previous element, swap if necessary

• Continue this process until the end of the array

• Repeat the process for the remaining elements

• Return the sorted wave array
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Q2. Maximum Sum BST
You are given a Binary Tree ‘root’. The given Binary Tree may or may not be a Binary Search Tree(BST) itself. Your task is to find the maximum sum of node values of any subtree that is a Bi...read more
Ans. 
The task is to find the maximum sum of node values of any subtree that is a Binary Search Tree(BST).
• Traverse the binary tree in a bottom-up manner

• For each node, check if it forms a BST and calculate the sum of its subtree

• Keep track of the maximum sum encountered so far

• Return the maximum sum
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Round duration - 135 minutes
Round difficulty - Hard

This was the final technical round, it was around 2.5 hours long and based on mostly DSA and little bit Projects, DBMS, OS. Josh mainly focus on DSA and on Tree Data Structure in interview.

Q1. Pair Sum in BST.
You are given a Binary Search Tree (BST) and a target value ‘K’. Your task is to check if there exist two unique elements in the given BST such that their sum is equal to the given target ...read more
Ans. 
The task is to check if there exist two unique elements in the given BST such that their sum is equal to the given target 'K'.
• Traverse the BST in-order and store the elements in a sorted array

• Use two pointers, one at the beginning and one at the end of the array

• Check if the sum of the elements at the two pointers is equal to the target 'K'

• If the sum is less than 'K', move the left pointer to the right

• If the sum is grea...read more
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Q2. Print Nodes at Distance K From a Given Node
You are given an arbitrary binary tree, a node of the tree, and an integer 'K'. You need to find all such nodes which have a distance K from the given no...read more
Ans. 
The task is to find all nodes in a binary tree that are at a distance K from a given node.
• Implement a function that takes the binary tree, target node, and distance K as input.

• Use a depth-first search (DFS) algorithm to traverse the tree and find the nodes at distance K.

• Keep track of the distance from the current node to the target node while traversing.

• When the distance equals K, add the current node to the result lis...read more
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Round duration - 20 minutes
Round difficulty - Easy

This was the simple 20 minutes round

Q1. Basic HR Questions
In this interviewer asked me about my family, residence and if I will have any issue in relocating to Gurgaon. After 30 minutes of this round they send me mail regarding my selection.
Ans. 
The candidate was asked about their family, residence, and willingness to relocate to Gurgaon.
• The interviewer wanted to know about the candidate's personal background and circumstances.

• The candidate's response may have influenced their selection.

• Examples of relevant information include family size, current residence location, and any potential challenges in relocating.

• The candidate's answer should demonstrate their fle
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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
You have been given the root of two binary trees ‘ROOT1’ and ‘ROOT2’. You need to find if the two trees are flip equivalent or not after performing some flip operations on ‘TREE...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
You are given an integer array/list ‘ARR’ of size 'N' that is sorted in ascending order. Your task is to return '1' if and only if you can split it...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
Ninja is given a few numbers, and he is being asked to rearrange the numbers so that every second element is greater than its left and right element.
Suppose the given array...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
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Q2. Puzzle
You have measure 4litre using 3 cups of 3,5 and 8 litres.
Ans. 
Tip 1 : Cross quesion the interviewer on whatever doubt You have like asked Is the water infinite.
Tip 2 : Before jumping to a soln always cross verify in your mind once.
Tip 3 : Keep on speaking whatever you think Never be on Doubt make it a healthy conversation.
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Round duration - 30 Minutes
Round difficulty - Easy

10:30 PM 
Interviewer was Cool.

Q1. Technical Question
This round was completely about my projects and my previous internships. There was lot of drilling on my projects like motive behind doing it.Futher improvement in Your project.
Ans. 
The interview focused on the candidate's projects and previous internships.
• Drilling on the motive behind the projects

• Discussion on further improvements in the projects
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Round duration - 5 minutes
Round difficulty - Easy

At 10:00 am

Q1. Basic HR Questions
No problems were asked just said do u want to ask about me or the company. And how was my interview experience.
Ans. 
The interviewer asked if there were any questions about them or the company, and how the interview experience was.
• Express interest in learning more about the interviewer's role and experience.

• Ask about the company culture and values.

• Inquire about the next steps in the interview process.

• Provide positive feedback about the interview experience.
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Round duration - 180 Minutes
Round difficulty - Medium

Q1. Maximum meetings
You are given the schedule of N meetings with their start time Start[i] and end time End[i]. But you have only 1 meeting room. So, you need to tell the meeting numbers you can organize in ...read more
Ans. 
For each test case, print the meeting numbers (Consider 1 based indexing) you organized in the given room, in the order in which you organized them such that the number of meetings is maximum.
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Q2. K subsets with equal sum
You are given an array of integers "ARR" of length 'N' and an integer 'K'. Your task is to find whether or not you can divide the array "ARR" in...read more
Ans. 
For each test case, print a single line containing “True” if it is possible to divide the array into ‘K' equal sum subsets, “False” otherwise. 

The output of each test case will be printed in a separate line.
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Q3. Merge k sorted lists
Given 'K' sorted linked lists, each list is sorted in increasing order. You need to merge all these lists into one single sorted list. You need to return the head of the final ...read more
Ans. 
For each test case, print a single line containing space-separated denoting the elements of the merged sorted list. The elements of the linked list must be separated by a single space and terminated by -1.

The output of each test case will be printed in a separate line.
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Q4. Sort A “K” Sorted Doubly Linked List
You’re given a doubly-linked list with N nodes, where each node deviates at max K position from its position in the sorted list. Your task is to sort this given doubly ...read more
Ans. 
For each test case print in a new line the sorted linked list, the elements of the sorted list should be single-space separated, terminated by -1.
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Q5. Duplicate Subtrees
You have been given a binary tree, you are supposed to return the root values of all the duplicate subtrees. For each duplicate subtree, you only need to return the root value of any one...read more
Ans. 
For each test case, print space-separated root node value of all the duplicate subtrees. If no duplicate subtree is present in the binary tree print ‘-1’. The order of the list of node values does not matter.

Print the output for each test case in a separate line.
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Round duration - 25 Minutes
Round difficulty - Medium

Q1. DBMS Question
Explains the concept of keys.
Ans. 
Tip 1 : Basic Knowledge of Database is needed
Tip 2 : Easy questions
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Q2. Puzzle
How do we measure forty-five minutes using two identical wires, each of which takes an hour to burn? We have matchsticks with us. The wires burn non-uniformly. So, for example, the two halves of wire...read more
Ans. 
Tip 1 : Lightstick 1 on both sides and stick 2 on one side.
Tip 2 : Stick 1 will be burnt out. Light the other end of stick 2.
Tip 3 : Stick 2 will be burnt out. Thus 45 minutes is completely measured
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Round duration - 15 Minutes
Round difficulty - Easy

Q1. Basic HR Questions
Tell me about yourself.
Tell me about different projects that you have worked on.
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