Morgan Stanley Software Developer Intern Interview Questions and Answers

3 questions of medium to hard coding questions.

Q1. Technical interview including SQL, one programming language, and dbms based questions. the interview went well and was of 90mins.
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Round duration - 100 minutes
Round difficulty - Medium

Test started at 04:00 PM sharp and complete the same by 06:00 PM.
The test duration is 100 minutes.
Environment (Amcat) is user friendly and understandable.
Web cam and microphone were also enabled.

Q1. 
Longest Substring with At Most K Distinct Characters
Given a string S of length N and an integer K, find the length of the longest substring that contains at most K distinct characters.
Input:
The first...read more
Ans. 
Find the length of the longest substring with at most K distinct characters in a given string.
• Use a sliding window approach to keep track of the characters and their counts within the window.

• Maintain a hashmap to store the characters and their frequencies.

• Update the window size and characters count as you iterate through the string.

• Return the maximum window size encountered for each test case.
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Q2. 
Find the Duplicate Number Problem Statement
Given an integer array 'ARR' of size 'N' containing numbers from 0 to (N - 2). Each number appears at least once, and there is one number that appears twice. Yo...read more
Ans. 
Find the duplicate number in an integer array containing numbers from 0 to (N - 2).
• Iterate through the array and keep track of the frequency of each number using a hashmap.

• Return the number that appears twice in the array.

• The duplicate number is always present in the given array.
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Round duration - 40 minutes
Round difficulty - Hard

This round was conducted on skype platform. I was shared the invitation link one day prior to the interview and also was told the name of my interviewer. I looked at the profile of the interviewer at linked.in and got a better understanding of what kind of person he was and prepared accordingly. The round was scheduled at 3 :00 pm on 5th Nov and I was eagerly waiting for the clock hands to reach 3 o'clock since morning and finally I went in front of him after wearing a white shirt and a black coat over it along with a tie over it.

Q1. 
Ninja and Binary String Problem Statement
Ninja has a binary string S of size N given by his friend. The task is to determine if it's possible to sort the binary string S in decreasing order by removing a...read more
Ans. 
Determine if a binary string can be sorted in decreasing order by removing non-adjacent characters.
• Iterate through the binary string and check if it can be sorted in decreasing order by removing non-adjacent characters.

• Keep track of the count of '1's and '0's in the string to determine if it can be sorted in decreasing order.

• If the count of '1's is greater than the count of '0's, the string can be sorted in decreasing ...read more
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Q2. 
Split the String Problem Statement
You are given a string str consisting of N lowercase alphabets. Your task is to determine if it is possible to divide the string into three non-empty substrings such tha...read more
Ans. 
Given a string, determine if it can be split into three non-empty substrings where one is a substring of the other two.
• Check if any substring of the string is a substring of the other two substrings.

• Iterate through all possible splits of the string and check for the condition.

• Use two pointers to find all possible substrings efficiently.
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Round duration - 40 minutes
Round difficulty - Easy

This round was scheduled on 15th Nov, almost after 10 days of the previous technical round. I got the confirmation of passing the previous round on 11th Nov and was asked to appear in this final round which was scheduled on 15th Nov at 11:00 am in the morning and it was going to be an HR round which probably was my favourite among all the other rounds. I prepared for by reading interview experiences available at coding ninjas and geeksforgeeks.

Round duration - 50 minutes
Round difficulty - Hard

Timing (10 am- 10:50 am)
For this round I had slightly more time than the last, due to the fact that the weekend fell in between.The interviewer was very very cool and helping this time, something which I kept at the last in my list of probable things that can happen during an interview. Duration of this round was around 50 minutes.

This time I had to face three technical questions and one general question on Finance banks.

Q1. 
Pair Sum Problem Statement
You are given an integer array 'ARR' of size 'N' and an integer 'S'. Your task is to find and return a list of all pairs of elements where each sum of a pair equals 'S'.
Note:
...read more
Ans. 
Find pairs of elements in an array that sum up to a given value, sorted in a specific order.
• Iterate through the array and for each element, check if the complement (S - current element) exists in a hash set.

• If the complement exists, add the pair to the result list.

• Sort the result list based on the criteria mentioned in the problem statement.
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Q2. 
Validate BST Problem Statement
Given a binary tree with N nodes, determine whether the tree is a Binary Search Tree (BST). If it is a BST, return true; otherwise, return false.
A binary search tree (BST)...read more
Ans. 
Validate if a binary tree is a Binary Search Tree (BST) or not.
• Check if the left subtree of a node contains only nodes with data less than the node's data.

• Check if the right subtree of a node contains only nodes with data greater than the node's data.

• Ensure both the left and right subtrees are also binary search trees.

• Traverse the tree in an inorder manner and check if the elements are in sorted order.

• Recursively valid...read more
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Round duration - 35 minutes
Round difficulty - Medium

There was only one interviewer for this round. He continuously interacted with me and was giving me some good situational problems that were not very easy to answer. Basically those were open-minded questions which can be answered oth ways and that's why I found it quiet hard as per my nature but at the end things went well for me.

Round duration - 90 Minutes
Round difficulty - Hard

Q1. 
Ways To Make Coin Change
Given an infinite supply of coins of varying denominations, determine the total number of ways to make change for a specified value using these coins. If it's not possible to make...read more
Ans. 
Implement a function to determine the total number of ways to make change for a specified value using given denominations.
• Use dynamic programming to keep track of the number of ways to make change for each value up to the target value.

• Iterate through each denomination and update the number of ways to make change for each value based on the current denomination.

• Return the total number of ways to make change for the targ...read more
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Round duration - 90 Miinutes
Round difficulty - Medium

I was asked 3 coding questions

Q1. How would you design a system like Facebook?
Ans. 
Designing a system like Facebook involves creating user profiles, news feeds, friend connections, messaging features, and more.
• Create user profiles with personal information, photos, and posts

• Implement a news feed algorithm to display relevant content to users

• Allow users to connect with friends and follow other users

• Include messaging features for private communication between users

• Implement notifications for likes, com...read more
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Q2. 
Sorted Linked List to Balanced BST Problem Statement
Given a singly linked list where nodes contain values in increasing order, your task is to convert it into a Balanced Binary Search Tree (BST) using th...read more
Ans. 
Convert a sorted singly linked list into a Balanced Binary Search Tree (BST) using the same data values.
• Create a function to convert the linked list to a BST by finding the middle element as the root and recursively building the left and right subtrees.

• Maintain a pointer to the head of the linked list and update it as nodes are processed.

• Use level order traversal to output the values of the BST nodes, representing NULL...read more
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Round duration - 60 Minutes
Round difficulty - Easy

This is HR + Technical Round
Started with tell me about yourself asked about projects in depth

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 pointer points back to a previous node.
• Use Floyd's Cycle Detection Algorithm to determine if there is a cycle in the linked list.

• Maintain two pointers, one moving at twice the speed of the other.

• If the two pointers meet at any point, there is a cycle in the linked list.
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