Morgan Stanley Java Developer Interview Questions and Answers

Q1. Quick sort - keep order same
Ans. 
Quick sort can be modified to maintain the order of equal elements, known as stable quick sort.
• Stable quick sort uses a modified partitioning method to keep equal elements in their original order.

• Example: For array ['apple', 'banana', 'apple', 'orange'], stable sort keeps the first 'apple' before the second.

• Using a stable sorting algorithm like merge sort can also achieve the same result if quick sort isn't stable.
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Q2. Reverse string with spaces but keep the space position intact
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Round 1 was an online hackerank coding test + technical MCQs.

It consisted of 5 MCQs + 1 SQL problem + 1 DSA problem based on queue + 1 Graph question + 1 java based question to create a REST API.

Round duration - 60 minutes
Round difficulty - Easy

Technical Interview round with questions on DSA and Java.

Q1. 
Max Element After Update Operations
Given an array A of size N, initialized with all zeros, and another array ARR of M pairs of integers representing operations. Each operation consists of a range where e...read more
Ans. 
Find the maximum element in an array after performing a series of increment operations on specified ranges.
• Initialize an array of size N with all zeros

• Iterate through the operations and increment elements within specified ranges

• Return the maximum element in the array after all operations
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Q2. Can you explain the internal working of a hash map in Java?
Ans. 
HashMap in Java is a data structure that stores key-value pairs and uses hashing to efficiently retrieve values based on keys.
• HashMap internally uses an array of linked lists to store key-value pairs.

• When a key-value pair is added, the key is hashed to find the index in the array where it will be stored.

• If multiple keys hash to the same index, a linked list is used to handle collisions.

• Retrieving a value involves hashi...read more
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Q3. Why do we need to override the equals and hashCode methods in Java?
Ans. 
Overriding equals and hashCode methods in Java is important for proper object comparison and hashing.
• Equals method is used to compare two objects for equality, while hashCode method is used to generate a unique integer value for an object.

• By overriding equals and hashCode methods, we can ensure that objects are compared based on their actual content rather than memory address.

• This is crucial for collections like HashMa...read more
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Round duration - 60 minutes
Round difficulty - Medium

Technical Interview round with questions based around Java.

Q1. How can you print even and odd numbers in increasing order using two threads in Java?
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Q2. What is the internal working of a CopyOnWrite ArrayList?
Ans. 
CopyOnWriteArrayList creates a new copy of the underlying array whenever an element is added, modified, or removed.
• CopyOnWriteArrayList is thread-safe and suitable for scenarios where reads are more frequent than writes.

• Adding, modifying, or removing elements in CopyOnWriteArrayList creates a new copy of the underlying array, ensuring thread safety.

• Iterators on CopyOnWriteArrayList operate on the original array and do ...read more
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Q3. What are the differences between Synchronized Collection and Concurrent Collection in Java?
Ans. 
Synchronized Collection is thread-safe but may have performance issues, while Concurrent Collection is optimized for concurrent access.
• Synchronized Collection uses synchronized keyword to achieve thread-safety, while Concurrent Collection uses non-blocking algorithms like CAS (Compare and Swap).

• Synchronized Collection locks the entire collection during modification, leading to potential performance bottlenecks, while C...read more
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