HashedIn by Deloitte Software Developer Interview Questions, Process, and Tips

Dp and strings questions along with array

Q1. LinkedList and Array medium level questions were asked
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Q2. Rotate a array k times
Ans. 
Rotate an array of strings k times
• Create a temporary array to store elements that will be rotated

• Use modulo operator to handle cases where k is greater than array length

• Update the original array with elements from the temporary array
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Q3. 2 sum using linked list
Ans. 
Use a hash table to find two numbers in a linked list that add up to a target sum.
• Traverse the linked list and store each node's value in a hash table along with its index.

• For each node, check if the difference between the target sum and the current node's value exists in the hash table.

• If it does, return the indices of the two nodes.

• Example: Given linked list 2 -> 4 -> 3 -> 5 and target sum 7, return indices 1 and 2.
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Q1. Dynamic programming and oops concept, dbms concepts were asked
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Q1. Tell me about yourself , why hashedin
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Round duration - 90 minutes
Round difficulty - Medium

There was three questions in the test. I was able to solve 2.5 questions. 2 Questions was of medium difficulty and one was easy.

Q1. 
Convert a Number to Words
Given an integer number num, your task is to convert 'num' into its corresponding word representation.
Input:
The first line of input contains an integer ‘T’ denoting the number o...read more
Ans. 
Convert a given integer number into its corresponding word representation.
• Implement a function that converts the given number into words by breaking it down into its individual digits and mapping them to their word representation.

• Handle special cases like numbers less than 20, multiples of 10, and numbers in the hundreds and thousands place.

• Ensure that there is a space between every two consecutive words and all charac
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Round duration - 60 Minutes
Round difficulty - Medium

Interviewer asked me 2 DSA question and 10 short answer type questions. 
Timing around 1 hour.
Interview was on zoom and we can use our own editor, for eg I used Vs Code.
Interviewer was very helpful. He helps me finding the edge cases.

Q1. 
Cycle Detection in a Singly Linked List
Determine if a given singly linked list of integers forms a cycle or not.
A cycle in a linked list occurs when a node's next points back to a previous node in the ...read more
Ans. 
Detect if a singly linked list forms a cycle by checking if a node's next points back to a previous node.
• Use Floyd's Tortoise and Hare algorithm to detect a cycle in the linked list.

• Maintain two pointers, slow and fast, where slow moves one step at a time and fast moves two steps at a time.

• If there is a cycle, the fast pointer will eventually meet the slow pointer.

• If the fast pointer reaches the end of the list (null),...read more
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Round duration - 60 Minutes
Round difficulty - Medium

Total duration of the round is 60 minutes.
Interview was on zoom. we can use any editor.
It was Design round.

Q1. How would you design a social media platform with features such as friend requests and posts?
Ans. 
Designing a social media platform with friend requests and posts.
• Implement user profiles with friend request functionality.

• Allow users to create and share posts on their profiles.

• Include news feed to display posts from friends.

• Implement notifications for friend requests and post interactions.

• Include privacy settings for posts and friend requests.

• Consider implementing features like comments, likes, and shares for posts.
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Round duration - 20 Minutes
Round difficulty - Easy

Duration of this round is 20 minutes.
Interview was on zoom.
Interviewer was very friendly.

Round duration - 90 minutes
Round difficulty - Medium

My test was scheduled at 2 pm and I received the test link at exactly 2 pm in my mail. The platform was quite user-friendly. The test consists of 3 coding question and I have solved all 3 of them.

Q1. 
Maximum Subarray Sum Problem Statement
Given an array of integers, determine the maximum possible sum of any contiguous subarray within the array.
Example:
Input:
array = [34, -50, 42, 14, -5, 86]
Out...read more
Ans. 
Find the maximum sum of any contiguous subarray within an array of integers.
• Iterate through the array and keep track of the maximum sum of subarrays encountered so far.

• At each index, decide whether to include the current element in the subarray or start a new subarray.

• Use Kadane's algorithm to efficiently find the maximum subarray sum.

• Example: For array [34, -50, 42, 14, -5, 86], the maximum subarray sum is 137.
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Q2. 
Last Stone Weight Problem Statement
We have a set collection of N stones, and each stone has a given positive integer weight. On each turn, select the two stones with the maximum weight and smash them toge...read more
Ans. 
Find the weight of the last stone remaining after smashing stones together.
• Sort the stones in descending order.

• Simulate the smashing process by repeatedly smashing the two heaviest stones until only one stone is left.

• Return the weight of the last stone, or 0 if no stone is left.
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Round duration - 60 minutes
Round difficulty - Medium

This round consists of questions based on DSA and CS fundamentals. The interviewer was very nice she helped me whenever I was shucked in the question. Apart from dsa questions were based on DAMS, CN, OOPS, OS, Github.

Q1. 
Detect and Remove Loop in Linked List
For a given singly linked list, identify if a loop exists and remove it, adjusting the linked list in place. Return the modified linked list.
Expected Complexity:
A...read more
Ans. 
Detect and remove loop in a singly linked list in place with O(n) time complexity and O(1) space complexity.
• Use Floyd's Tortoise and Hare algorithm to detect the loop in the linked list.

• Once the loop is detected, find the start of the loop using the same algorithm.

• Adjust the pointers to remove the loop and return the modified linked list.

• Example: For input 5 2 and elements 1 2 3 4 5, output should be 1 2 3 4 5.
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Round duration - 30 minutes
Round difficulty - Medium

It was the HR Interview and consists of basic HR interview questions.

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 Problem
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 chocolates as possible ...read more
Ans. 
Find the maximum number of chocolates that can be collected by two friends moving in a grid.
• Start from the top-left and top-right corners, move diagonally down to collect chocolates

• Calculate the total chocolates collected by each friend and sum them up for the final result

• Consider all possible paths for both friends to maximize the total chocolates collected
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Q2. 
Trailing Zeros in Factorial Problem
Find the number of trailing zeroes in the factorial of a given number N.
Input:
The first line contains an integer T representing the number of test cases.
Each of the...read more
Ans. 
Count the number of trailing zeros in the factorial of a given number.
• Trailing zeros are created by pairs of 2 and 5 in the factorial.

• Count the number of 5s in the prime factorization of N to find the trailing zeros.

• For example, for N=10, there are 2 trailing zeros as there are two 5s in the prime factorization of 10.
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Q3. 
Find K'th Character of Decrypted String
You are given an encrypted string where repeated substrings are represented by the substring followed by its count. Your task is to find the K'th character of the d...read more
Ans. 
Given an encrypted string with repeated substrings represented by counts, find the K'th character of the decrypted string.
• Parse the encrypted string to extract substrings and their counts

• Iterate through the substrings and counts to build the decrypted string

• Track the position in the decrypted string to find the K'th character
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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 Problem Statement
Given a sequence of numbers, the task is to identify all the leaders within this sequence. An element is considered a leader if it is strictly greater than all the el...read more
Ans. 
Identify all the leaders in a sequence of numbers, where a leader is greater than all elements to its right.
• Iterate through the sequence from right to left, keeping track of the maximum element encountered so far.

• If an element is greater than the maximum element encountered so far, it is a leader.

• Add the leaders to a result sequence while maintaining the original order.

• The rightmost element is always a leader.
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Q2. 
Find Two Missing Numbers Problem Statement
Given an array of unique integers where each element is in the range [1, N], and the size of the array is (N - 2), there are two numbers missing from this array....read more
Ans. 
Given an array of unique integers with two missing numbers, find and return the missing numbers.
• Iterate through the array and mark the presence of each number in a separate boolean array.

• Iterate through the boolean array to find the missing numbers.

• Return the missing numbers in increasing order.
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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.
Input:
The first line of input contains an integer 'T' representing the numbe...read more
Ans. 
Reverse a singly linked list of integers in O(N) time and O(1) space complexity.
• Iterate through the linked list, reversing the pointers to point to the previous node instead of the next node.

• Use three pointers to keep track of the current, previous, and next nodes while reversing the list.

• Update the head of the reversed linked list as the last node encountered during the reversal process.

• Example: Given 1 -> 2 -> ...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. Design a music player similar to Spotify.
Ans. 
Design a music player similar to Spotify.
• Implement user authentication for personalized playlists and recommendations

• Create a user-friendly interface with features like search, shuffle, repeat, and create playlists

• Integrate a recommendation system based on user listening history and preferences
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Round duration - 30 minutes
Round difficulty - Easy

Interviewer was very friendly
And, timing was around 12.30 PM

Q1. Why should we hire you?
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Q2. What do you know about the company?
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Q1. Leetcode easy - medum questions
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Q2. DSA questions - linkedlist, tree etc
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Q1. Design a database for instagram
Ans. 
Database design for Instagram platform
• Create tables for users, posts, comments, likes, followers, and hashtags

• Use primary and foreign keys to establish relationships between tables

• Include fields such as user_id, post_id, comment_id, like_id, follower_id, and hashtag_id

• Implement indexes for faster data retrieval

• Consider scalability and performance optimization techniques
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Q1. Explain how would you react under a condition where your colleague does not agree your ideas
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Round duration - 90 minutes
Round difficulty - Medium

There were 3 coding questions. questions were implemented based on arrays and trees
Question 1 was Easy
Question 2 was Medium
Question 3 was Medium
all 3 questions were necessary to be selected for the next round.

Q1. 
Convert Binary Tree to Mirror Tree Problem Statement
Given a binary tree, convert this binary tree into its mirror tree. A binary tree is a tree in which each parent node has at most two children. The mir...read more
Ans. 
Convert a binary tree into its mirror tree by interchanging left and right children of non-leaf nodes.
• Traverse the binary tree in a recursive manner.

• Swap the left and right children of each non-leaf node.

• Continue this process until all nodes are visited.

• Example: Input binary tree: 1 2 3 4 -1 5 6 -1 7 -1 -1 -1 -1 -1 -1, Output mirror tree: 1 3 2 6 5 4 -1 -1 -1 -1 -1 7 -1 -1 -1
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Q2. 
Min Jumps Problem Statement
In Ninja town, represented as an N * M grid, people travel by jumping over buildings in the grid's cells. Santa is starting at cell (0, 0) and must deliver gifts to cell (N-1, ...read more
Ans. 
Santa needs to find the quickest path to deliver gifts in Ninja town by jumping over buildings with least travel time.
• Santa starts at (0, 0) and needs to deliver gifts to (N-1, M-1) on Christmas Eve.

• Santa can jump to (x+1, y+1), (x+1, y), or (x, y+1) from any cell (x, y) within grid boundaries.

• Travel time between two buildings equals the absolute difference in their heights.

• Find the quickest path with least travel time...read more
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Round duration - 60 minutes
Round difficulty - Medium

It was DSA based round where there was some discussion on the project followed by 2 coding questions, I had to explain my approach and write the code on Google Docs.

Q1. 
Anagram Pairs Verification Problem
Your task is to determine if two given strings are anagrams of each other. Two strings are considered anagrams if you can rearrange the letters of one string to form the...read more
Ans. 
Check if two strings are anagrams of each other by comparing their sorted characters.
• Sort the characters of both strings and compare them.

• Use a dictionary to count the frequency of characters in each string and compare the dictionaries.

• Ensure both strings have the same length before proceeding with the comparison.

• Example: For input 'str1 = "spar", str2 = "rasp"', the output should be True.
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Q2. 
Longest Mountain Subarray Problem Statement
Given an array of integers denoting the heights of the mountains, find the length of the longest subarray that forms a mountain shape.
A mountain subarray is d...read more
Ans. 
Find the length of the longest mountain subarray in an array of integers.
• Identify peaks in the array where the elements transition from ascending to descending order.

• Calculate the length of the mountain subarray starting from each peak.

• Track the length of the longest mountain subarray found so far.

• Consider edge cases like when there are no mountains in the array.
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Round duration - 75 minutes
Round difficulty - Easy

This round mainly revolved around a system design for an e-commerce website, then some DBMS queries followed by interview questions on OS, DBMS, and Computer Networks. Also there was some discussion of project, how it works, why I made the project, etc.

Round duration - 30 Minutes
Round difficulty - Easy

Some HR questions were asked like other offers, Why do you wanna join Hashedin, and strengths and weaknesses.
After that a puzzle was asked which I correctly answered